讨论下列讨论函数的连续性例题f(x)=大括号sin3x/x,x<0 2x+3,x≥0

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Copyright (C) 2017 Baidu大一微积分习题答案
大一微积分习题答案
范文一:一、填空题P(x)P(x)?6x3lim?3,则P(x)?
?21.设P(x)是x的多项式,且lim,2x?0x??xx?3222.limx?x?x))?
6x?2x?3x↑x???6??2?3.lim?1???
e3x??x??x3?ax?x?4?A,则有a?
4,-2 4.设limx?1x?12sinx5.设f(x)?xsin?,则limf(x)?
2x??xx1x2?sin3x?sinx?
1 6.limx?033x2?x7.函数y?的间断点是x?1(x?1)(x?2)18.为使函数f?x???tanx在点x?0处连续,应补充定义f?0??x3?x?x?0在x?0处连续,则参数K?
e?3 9.设函数y??(1?x)?x?0?K?x?ax?010.函数f(x)??x在点x?0处连续,则a?
2?e?1x?0二、单项选择题1.设xn?0,且limxn存在,则limxn②n??n??x32①?0
④?0 2.极限limex?11?
④0 3.lim(1?x)1?
④x?0x??x?1?1①e;
④e?1?1x?limxsinx?3的连续区间是__________________
②x?1x?2①???,?2????2,?1????1,???
②?3,???③???,?2????2,???
④???,?1????1,???x?x?15.函数y?的不连续点有③?x?1x?14.y?①2个
④4个以上6.下列函数中,.当x?0时,与无穷小量x相比是高阶无穷小量的是___________;是等价无穷小量的是__________________
①,②2①1?cosx
④sin2x7.当x?0时,sinx与|x|相比是
②①高阶无穷小量
②低阶无穷小量
③同阶但不等价的无穷小量
④等价无穷小量?8.当x?0时,1?cos2x与x2相比是②
①高阶无穷小量
②同阶但不等价的无穷小量③低阶无穷小量
④等价无穷小量?sin3x??,x?09.设f?x???
为连续函数,则k =_______________
② x?kx?0?① 1
④ 310.函数f?x?在点x0处有定义是f?x?当x?x0时极限存在的④ ①充分但非必要条件
②必要但非充分条件③充分必要条件
④既非充分又非必要条件11.当x?0时,下列函数中比x高阶的无穷小量是
②①x?sinx
④ln?1?x? 12.当x?0时,下列函数中为无穷小量的是
①x?sin1111②x?sin
④?sinx xxxx13.当x??时,下列函数中为无穷小量的是
③1111②x?sin
④?sinx xxxx14.设在某个极限过程中函数f?x?与g?x?均是无穷大量,则下列函数中哪一个也必是无穷①x?sin大量
③ ① f?x??g?x?
② f?x??g?x?
③ f?x??g?x?
④x?x0x?x0f?x??b,limf?x??c,则函数f?x?在点x0处连续的充分必要15.设f?x0??a,lim??条件是
④a?b?cf?x? gx?x2?1x1?1?16.x?1是f(x)??x?1e?0?x?1的
④ x?1①连续点
②跳跃间断点
③可去间断点
④无穷间断点三、求下列极限1.lim(x?1?x)?limx???221x?1?x2x????02.lim(x?1?x)???x???3.lim(x?2x?2?x???2x2?2x?2)4x2?limx???x?2x?2?x?2x?22?lim41?2222?2???2xxxxx????24.lim?arctanx?arcsin??0?x???1?x?7(x?1)2?(2x?1)2?(3x?1)2???(10x?1)25.lim(?)x??2(10x?1)(11x?1)nnn?2???2)
6.lim(2n??n?1n?2n?nnnn?2???2[解]
n?1n?2n?nnnnnnn?2???2?xn?2?2???2
因为 2n?nn?nn?nnnnnn?xn?1,由于lim?1,所以由夹逼定理,得limxn?1 即n??n??n?1n?1n?7.设lim??2006,求?,?n??n?(n?1)?[解]
原式左端?limn??n?????1??1?1????n1?1???o???n?1??1????n?n??????n???n?1?lim?(????1)n????1???n??1???o???n??n???由于极限存在,故????1。??,????1? ??2006
????四、分析题|sinx|1.讨论极限limx?0x|sinx||sinx|?1lim??1,故原极限不存在。 [解]
因为lim,x?0?x?0?xxx2?12.求y?2的间断点,并判别间断点的类型。x?3x?2x2?1x2?12??2,lim2?? [解]
因为x?3x?2?(x?1)(x?2),而lim2x?1x?3x?2x?2x?3x?2因此有间断点:x?1为可去间断点,x?2为无穷间断点。.13.求函数y?6x?的连续区间,若有间断点,试指出间断点的类型。x[解]
函数的连续区间为(??,0)?(0,??),点x?0为函数的第二类无穷间断点。n???limn?4.讨论函数f(x)?lim??x?1??t?xt?1??tx?ttx?t的连续性。t令y?x?tt?1x?txx?yx?t??x?1??[解]
f(x)?lim?lim?1?y?y(x?1)?ex?1 ??lim?1???t?xt?1t?xy?0t?1????在点x?1处没有定义,是间断点,故f(x)的连续区间为(??,1)?(1,??),点x?1为f(x)的第二类无穷间断点。?cosxx?0在点x?0处的连续性。?x?1x?0f(x)?limcosx?1,limf(x)?lim(x?1)?1 [解]
?lim????5.讨论函数f(x)??x?0x?0x?0x?0∴ f(x)在点x?0处连续性。?a?a?xx?0??x6.设函数y?f?x???
(a?0)cosx?x?0??x?2(1)当a取何值时,点x?0是函数f?x?的间断点?是何种间断点? (2)当a取何值时,函数f?x?在???,???上连续?为什么?1cosx1f(x)?lim?, [解](1)在点x?0处,f(0)?,lim??x?0x?02x?22a?a?x11lim f(x)?lim?lim??x?0?x?0?x?0xa?a?x2af(x)?limf(x),所以点x?0是f?x?的跳跃间
当a?0且a?1时,由于lim??x?0x?0断点。f(x)?limf(x)?f(0),则f?x?在点x?0处连续。
(2)当a?1时,由于lim??又因为在(??,0)或(0,??)上,f?x?为初等函数,所以连续。 故当a?1时,函数f?x?在???,???上连续。x?0x?0?1?x?1x?0??0?x?1 7.设函数y?f?x???x??a1?x?4??(1)求函数f?x?的定义域;(2)讨论函数f?x?在点x?0处的极限是否存在?为什么?(3)a为何值时,函数f?x?在点x?1处连续?并求函数f?x?的连续区间;(4)画出函数y?f?x?的图形。 [解](1)Df?(??,?1)?(?1,4]1f(x)?limx?0,所以limf(x)不存在 ?1,limx?0x?0?x?0?x?0x?0x?1f(x)?limx?1,limf(x)?lima?a,
(3)在点x?1处,f(1)?a,lim????f(x)?lim
(2)因为lim??f(x)?limf(x)?f(1),
所以,当a?1时,lim即函数f?x?在点x?1处连续。 ??此时,f?x?的连续区间为:(??,?1)?(?1,4](4)略 五、证明题1.证明方程x?7x?4在区间(1,2)内至少有一个实根。5[证]
设f(x)?x?7x?4,f(x)在[1,2]上连续,5x?1x?1x?1x?1x?1x?1又f(1)??10?0,f(2)?14?0,由零点定理知,在(1,2)内至少存在一点?,使得f(?)?0,即?5?7??4?0,故方程x?7x?4在区间(1,2)内至少有一个实根。2.证明:方程x?2sinx?k(k?0)至少有一个正根。 [证]
设f(x)?x?2sinx?k?C[0,??)因为f(0)??k?0,f(k?3)?3?2sin(k?3)?0故由零点定理知,???(0,k?3),使得f(?)?0,所以方程x?2sinx?k至少有一正根。3.证明方程x?asinx?2(a?0)至少有一个正根,并且不超过a?2。 [证]
设f(x)?x?asinx?2,下面分两种情形来讨论:情形1 若 sin(a?2)?1,则因为a?0,故a?2是方程x?asinx?2(a?0)的正根,并且不超过a?2。情形2 若sin(a?2)?1,则因a?0,故f(a?2)?a[1?sin(a?2)]?0,5f(0)??2?0,又因f(x)在[0,a?2]上连续,故由零点定理知,???(0,a?2),使得f(?)?0,因此?是方程x?asinx?2(a?0)的正根,并且不超过a?2。4.设n为正整数,函数f(x)在[0,n]上连续,且f(0)?f(n),证明存在数a,a?1?[0,n],使得f(a)?f(a?1)。[证] 若n?1,即f(0)?f(1),取a?0,a?1?1?[0,1],结论成立。若n?2,作辅助函数F(x)?f(x?1)?f(x),易知F(x)在[0,n?1]上连续,因为F(0)?F(1)???F(n?1)?[f(1)?f(0)]?[f(2)?f(1)]?[f(3)?f(2)]???[f(n)?f(n?1)]?f(n)?f(0)?0则n个实数F(0),F(1),?,F(n?1)全部为零或同时有正数与负数,(1)若这些数全部为零,即F(0)?F(1)???F(n?1)?0,则结论成立。(2)若这些数中有正数与负数,即有某个F(i)?0,F(j)?0,(i?j,0?i,j?n?1)
于是由零点定理可知,在i与j之间存在一点a(显然a,a?1?[0,n]),使得F(a)?0,即 f(a)?f(a?1)
###原文地址:一、填空题P(x)P(x)?6x3lim?3,则P(x)?
?21.设P(x)是x的多项式,且lim,2x?0x??xx?3222.limx?x?x))?
6x?2x?3x↑x???6??2?3.lim?1???
e3x??x??x3?ax?x?4?A,则有a?
4,-2 4.设limx?1x?12sinx5.设f(x)?xsin?,则limf(x)?
2x??xx1x2?sin3x?sinx?
1 6.limx?033x2?x7.函数y?的间断点是x?1(x?1)(x?2)18.为使函数f?x???tanx在点x?0处连续,应补充定义f?0??x3?x?x?0在x?0处连续,则参数K?
e?3 9.设函数y??(1?x)?x?0?K?x?ax?010.函数f(x)??x在点x?0处连续,则a?
2?e?1x?0二、单项选择题1.设xn?0,且limxn存在,则limxn②n??n??x32①?0
④?0 2.极限limex?11?
④0 3.lim(1?x)1?
④x?0x??x?1?1①e;
④e?1?1x?limxsinx?3的连续区间是__________________
②x?1x?2①???,?2????2,?1????1,???
②?3,???③???,?2????2,???
④???,?1????1,???x?x?15.函数y?的不连续点有③?x?1x?14.y?①2个
④4个以上6.下列函数中,.当x?0时,与无穷小量x相比是高阶无穷小量的是___________;是等价无穷小量的是__________________
①,②2①1?cosx
④sin2x7.当x?0时,sinx与|x|相比是
②①高阶无穷小量
②低阶无穷小量
③同阶但不等价的无穷小量
④等价无穷小量?8.当x?0时,1?cos2x与x2相比是②
①高阶无穷小量
②同阶但不等价的无穷小量③低阶无穷小量
④等价无穷小量?sin3x??,x?09.设f?x???
为连续函数,则k =_______________
② x?kx?0?① 1
④ 310.函数f?x?在点x0处有定义是f?x?当x?x0时极限存在的④ ①充分但非必要条件
②必要但非充分条件③充分必要条件
④既非充分又非必要条件11.当x?0时,下列函数中比x高阶的无穷小量是
②①x?sinx
④ln?1?x? 12.当x?0时,下列函数中为无穷小量的是
①x?sin1111②x?sin
④?sinx xxxx13.当x??时,下列函数中为无穷小量的是
③1111②x?sin
④?sinx xxxx14.设在某个极限过程中函数f?x?与g?x?均是无穷大量,则下列函数中哪一个也必是无穷①x?sin大量
③ ① f?x??g?x?
② f?x??g?x?
③ f?x??g?x?
④x?x0x?x0f?x??b,limf?x??c,则函数f?x?在点x0处连续的充分必要15.设f?x0??a,lim??条件是
④a?b?cf?x? gx?x2?1x1?1?16.x?1是f(x)??x?1e?0?x?1的
④ x?1①连续点
②跳跃间断点
③可去间断点
④无穷间断点三、求下列极限1.lim(x?1?x)?limx???221x?1?x2x????02.lim(x?1?x)???x???3.lim(x?2x?2?x???2x2?2x?2)4x2?limx???x?2x?2?x?2x?22?lim41?2222?2???2xxxxx????24.lim?arctanx?arcsin??0?x???1?x?7(x?1)2?(2x?1)2?(3x?1)2???(10x?1)25.lim(?)x??2(10x?1)(11x?1)nnn?2???2)
6.lim(2n??n?1n?2n?nnnn?2???2[解]
n?1n?2n?nnnnnnn?2???2?xn?2?2???2
因为 2n?nn?nn?nnnnnn?xn?1,由于lim?1,所以由夹逼定理,得limxn?1 即n??n??n?1n?1n?7.设lim??2006,求?,?n??n?(n?1)?[解]
原式左端?limn??n?????1??1?1????n1?1???o???n?1??1????n?n??????n???n?1?lim?(????1)n????1???n??1???o???n??n???由于极限存在,故????1。??,????1? ??2006
????四、分析题|sinx|1.讨论极限limx?0x|sinx||sinx|?1lim??1,故原极限不存在。 [解]
因为lim,x?0?x?0?xxx2?12.求y?2的间断点,并判别间断点的类型。x?3x?2x2?1x2?12??2,lim2?? [解]
因为x?3x?2?(x?1)(x?2),而lim2x?1x?3x?2x?2x?3x?2因此有间断点:x?1为可去间断点,x?2为无穷间断点。.13.求函数y?6x?的连续区间,若有间断点,试指出间断点的类型。x[解]
函数的连续区间为(??,0)?(0,??),点x?0为函数的第二类无穷间断点。n???limn?4.讨论函数f(x)?lim??x?1??t?xt?1??tx?ttx?t的连续性。t令y?x?tt?1x?txx?yx?t??x?1??[解]
f(x)?lim?lim?1?y?y(x?1)?ex?1 ??lim?1???t?xt?1t?xy?0t?1????在点x?1处没有定义,是间断点,故f(x)的连续区间为(??,1)?(1,??),点x?1为f(x)的第二类无穷间断点。?cosxx?0在点x?0处的连续性。?x?1x?0f(x)?limcosx?1,limf(x)?lim(x?1)?1 [解]
?lim????5.讨论函数f(x)??x?0x?0x?0x?0∴ f(x)在点x?0处连续性。?a?a?xx?0??x6.设函数y?f?x???
(a?0)cosx?x?0??x?2(1)当a取何值时,点x?0是函数f?x?的间断点?是何种间断点? (2)当a取何值时,函数f?x?在???,???上连续?为什么?1cosx1f(x)?lim?, [解](1)在点x?0处,f(0)?,lim??x?0x?02x?22a?a?x11lim f(x)?lim?lim??x?0?x?0?x?0xa?a?x2af(x)?limf(x),所以点x?0是f?x?的跳跃间
当a?0且a?1时,由于lim??x?0x?0断点。f(x)?limf(x)?f(0),则f?x?在点x?0处连续。
(2)当a?1时,由于lim??又因为在(??,0)或(0,??)上,f?x?为初等函数,所以连续。 故当a?1时,函数f?x?在???,???上连续。x?0x?0?1?x?1x?0??0?x?1 7.设函数y?f?x???x??a1?x?4??(1)求函数f?x?的定义域;(2)讨论函数f?x?在点x?0处的极限是否存在?为什么?(3)a为何值时,函数f?x?在点x?1处连续?并求函数f?x?的连续区间;(4)画出函数y?f?x?的图形。 [解](1)Df?(??,?1)?(?1,4]1f(x)?limx?0,所以limf(x)不存在 ?1,limx?0x?0?x?0?x?0x?0x?1f(x)?limx?1,limf(x)?lima?a,
(3)在点x?1处,f(1)?a,lim????f(x)?lim
(2)因为lim??f(x)?limf(x)?f(1),
所以,当a?1时,lim即函数f?x?在点x?1处连续。 ??此时,f?x?的连续区间为:(??,?1)?(?1,4](4)略 五、证明题1.证明方程x?7x?4在区间(1,2)内至少有一个实根。5[证]
设f(x)?x?7x?4,f(x)在[1,2]上连续,5x?1x?1x?1x?1x?1x?1又f(1)??10?0,f(2)?14?0,由零点定理知,在(1,2)内至少存在一点?,使得f(?)?0,即?5?7??4?0,故方程x?7x?4在区间(1,2)内至少有一个实根。2.证明:方程x?2sinx?k(k?0)至少有一个正根。 [证]
设f(x)?x?2sinx?k?C[0,??)因为f(0)??k?0,f(k?3)?3?2sin(k?3)?0故由零点定理知,???(0,k?3),使得f(?)?0,所以方程x?2sinx?k至少有一正根。3.证明方程x?asinx?2(a?0)至少有一个正根,并且不超过a?2。 [证]
设f(x)?x?asinx?2,下面分两种情形来讨论:情形1 若 sin(a?2)?1,则因为a?0,故a?2是方程x?asinx?2(a?0)的正根,并且不超过a?2。情形2 若sin(a?2)?1,则因a?0,故f(a?2)?a[1?sin(a?2)]?0,5f(0)??2?0,又因f(x)在[0,a?2]上连续,故由零点定理知,???(0,a?2),使得f(?)?0,因此?是方程x?asinx?2(a?0)的正根,并且不超过a?2。4.设n为正整数,函数f(x)在[0,n]上连续,且f(0)?f(n),证明存在数a,a?1?[0,n],使得f(a)?f(a?1)。[证] 若n?1,即f(0)?f(1),取a?0,a?1?1?[0,1],结论成立。若n?2,作辅助函数F(x)?f(x?1)?f(x),易知F(x)在[0,n?1]上连续,因为F(0)?F(1)???F(n?1)?[f(1)?f(0)]?[f(2)?f(1)]?[f(3)?f(2)]???[f(n)?f(n?1)]?f(n)?f(0)?0则n个实数F(0),F(1),?,F(n?1)全部为零或同时有正数与负数,(1)若这些数全部为零,即F(0)?F(1)???F(n?1)?0,则结论成立。(2)若这些数中有正数与负数,即有某个F(i)?0,F(j)?0,(i?j,0?i,j?n?1)
于是由零点定理可知,在i与j之间存在一点a(显然a,a?1?[0,n]),使得F(a)?0,即 f(a)?f(a?1)
范文二:极限习题解答1. 试写出一个由[0,1]到(0,1)的一一对应映射. 解:?1?,?2?1,f(x)??3?1,?n?2?x,?n??x?0x?11x?,n?2,3,4?n其他2.求极限 lim(a1n?1?a2n?2???amn?m),其中a1?a2???am?0. 解:n??k?1lim?akn?k=lim?akn?k?akn?1mm?n??k?1m?=lim?akn??k?1k?1=0.n?k?n?13.用极限定义证明 (1)n??lim(n?1?n)?0证明:???0,欲使 |n?1?n|??.由于|n?1?n|?11n?1?n?1n,故只需?1???,即 n??2? 便可. n???取 N????1,则当n>N时,有 |n?1?n|??. 2?1????故 lim(n?1?n)?0.n??(2)lim(n)?1n??il(n)?1等价于liman?0.证明: 因为 n?1,令n?1?an,则an?0,且mn??n??由于112n2n?(1?an)n?1?nan?n(n?1)an???an?n(n?1)an,22所以
0?an?2. n?1因此 ???0,取 N?1???2?,则当 n?N时,有 2????0?an??,故 liman?0.从而 lim(n)?1.n??n??4.利用夹逼定理求极限 (1)lim1?3?5???(2n?1);n??2?4?6???(2n)解法1:因为1?33?5??3,4??3?5,…,22(2n?1)?(2n?1)2n??(2n?1)(2n?1),22?所以0?1?3?5???(2n?1)1?3?5???(2n?1)1, ??2?4?6???(2n)?3?3?5??7???(2n?1)(2n?1))2n?112n?1?0,所以lim1?3?5???(2n?1)?0.n??2?4?6???(2n)由于limn??解法2:令an?1?3?5???(2n?1),则2?4?6???(2n)20?an?1?3?3?5?5???(2n?1)?(2n?1)2n?1, ?22?42?62???(2n)2(2n)2易知 lim1?3?5???(2n?1)?0.n??2?4?6???(2n)21?3?5???(2n?1)246?1?3?5???(2n?1)?2n1???解法3:由,可知 ?,进而得??2?4?6???(2n)?2?4?6???(2n)??到lim1?3?5???(2n?1)?0.n??2?4?6???(2n)11?m?mnn????n?n(2)lim???ak????ak??,其中ak?0(k?1,2,?,m).n????k?1k?1????????解:令a?min{ak},A?max{ak},则1?k?m1?k?mA?1?1???n??n????ak????ak??m?A??, a?k?1?a???k?1?m1nm1n11?m?mnn1????n?n由于limm?1,所以lim???ak????ak???A?.n??n????ak?1k?1????????5.设un?(1?)1nn?1(易知数列{un}收敛于e).(1)研究数列{un}的单调性; (2)利用(1)的结果证明解:(1)111?ln(1?)?对于任意正整数n都成立. n?1nn1un?(1?)n?1n1n1(1?)1?un?1?()n?n?(1?1)n?n ?2n?1unn?1n?1n?1(1?)1?nnnnn3?n2?n?(1?2)??3?12n?1n?1n?n?n?1所以数列{un}单调减. (2)1111? lim(1?)n?1?lim(1?)n?e,且(1?)n?1单调减,(1?)n单调增,x??x??nnnn11? (1?)n?1?e,(1?)n?enn分别两边取对数111(n?1)ln(1?)?1?ln(1?)?nnn?1111n?ln(1?)?e?ln(1?)?nnn所以111?ln(1?)? n?1nn6.证明:若单调数列具有收敛的子列,则此单调数列收敛.证明:不妨设?an?为一单调增加数列,ank为?an?的一个子列,且limank?A.k????????,?limank?A,k????N0?0,当k>N0时,有ank?A??.??an?单增,且nk?k?当n?nN0?N0时,有A-??anN?an?对于n?nN0,总存在kn使nkn?n?an?ank????a?为有界单增列,其极限值A?sup?a?又?ank有极限,则有界nknk?an?ank?A?当n?nN0时,有A-??an?A即liman?Ak??7.设an?pp1p2?2???n(n?1,2,?),其中?pk?是一有界非负数列,试证数列?an?收n101010敛.证法1:单调有界收敛定理. 设0?pk?M,则pp1p211?1?2???n?M?????n?10102n1?M10??M, ?9?101?1101?10?an?即数列?an?有界.又易知数列?an?单增,所以数列?an?收敛. 证法2:Cauchy收敛准则.pn?110n?1pn?210n?2pn?m10n?mM10n?11?110m?1M,所以任给??0,由n91101?10由于an?m?an??????1MM得 . n?log??9?10n9取N??log??1,则对于任意的n?N,m?0,均有an?m?an?9????M?1M即数列?an???,n910是一Cauchy列,所以收敛.8.设bn?a0?a1q?a2q2???anqn,其中q?1且数列?ak?有界,试证数列?bn?收敛. 证明:Cauchy收敛准则.设ak?M,则1?qm1?qMn?1. q1?qbn?m?bn?an?1qn?1?an?2qn?2???an?mqn?m?Mqn?1?由此易证数列?bn?是一Cauchy列,所以收敛.9.若数列{an}满足 an?1?an?qan?an?1(n?1,2,?),其中0?q?1,试证数列{an}收敛.证明: ???0,因为an?m?an?an?m?an?m?1?an?m?1?an?m?2???an?1?an?qm?1?qm?2???q?1an?1?ana2?a1n?11?qmn?1?qa2?a1?q?Mqn,1?q1?q所以当取 N??logq?1,且n?N时,有an?m?an??对任意的m?0都成立. ?M??即数列{an}为柯西列,所以收敛.10.设an?0(?n),lim(a1?a2???an)???,且数列{an}单调减,证明n?????a?a3???an2?1li1?.1 n??a?a???a24n2证明:容易看出数列{an}有界(an?0(?n),单调减).a2?a4???a2n?1(a2?a2?a4?a4??a2n?a2n)21?(a2?a3?a4?a5??a2n?a2n?1)2? lim(a1?a2???an)???n??? lim(a2?a3??a2n?1)???n???lim(a2?a4???a2n)???n??同样 lim(a1?a3???a2n?1)???n??因为数列单调减,于是:0?a1?a3???a2n?1a?(a2?a3)?(a4?a5)???a2n?1?1a2?a4???a2na2?a4???a2na1??0a2?a4???a2n由夹逼定理 lim(n??a1?a3???a2n?1?1)?0,a2?a4???a2n所以 lima1?a3???a2n?1?1.n??a?a???a242nn??11.证明Stolz定理:设?an?和?bn?为两个数列,若{bn}单调增加,且limbn???,liman?1?ana?A,则lim?A.n??bn??bnn?1?bn证法1:令cn?an?an?1?A,则limcn?0,即对???0,?N?0,当n?N时,n??bn?bn?1cn??.由于an?an?1?(cn?A)(bn?bn?1)?an?2?(cn?1?A)(bn?1?bn?2)?(cn?A)(bn?bn?1)???aN?(cN?1?A)(bN?1?bN)???(cn?1?A)(bn?1?bn?2)?(cn?A)(bn?bn?1)?aN?cN?1(bN?1?bN)???cn?1(bn?1?bn?2)?cn(bn?bn?1)?A(bn?bN),所以cN?1bN?1?bN???cn?1bn?1?bn?2?cnbn?bn?1anaN?AbN?A??bnbnbn??aN?AbNb?bN??nbnbnaN?AbN??,bnaN?AbN??.bn因为 limbn???,所以对于上述??0,?N1?0,当n?N1时,n??取N2?max{N,N1},则当n?N2时,ana?A?2?,即limn?A.n??bnbn证法2:???0,因为 limn??xn?1?xn?A,所以 ?N3??, ?n?N3,有:yn?1?ynxn?1?xn?A??, 即yn?1?ynA???xn?1?xn?A??yn?1?yn取n?N?1,进行递推A???xN?2?xN?1?A??,即yN?2?yN?1(A??)(yN?2?yN?1)?xN?2?xN?1?(A??)(yN?2?yN?1)(A??)(yN?3?yN?2)?xN?3?xN?2?(A??)(yN?3?yN?2)?(A??)(yn?yn?1)?xn?xn?1?(A??)(yn?yn?1)以上各式相加,得:(A??)(yn?yN?1)?xn?xN?1?(A??)(yn?yN?1)即:(A??)(yn?yN?1)?xN?1?xn?(A??)(yn?yN?1)?xN?1同除以yn 则:(A??)(1?即:yN?1xN?1xnyx)???(A??)(1?N?1)?N?1 ynynynynyn(A??)(?因为:yN?1xN?1xyx)????n?A?(A??)(?N?1)?N?1?? ynynynynynlimyn???x???limx??yN?1?0 ynlimxN?1?0x??yn所以,???0,?N1?0,n?N1时 ???(A??)(?yN?1)??, yn???0,?N2?0,n?N2时 ???xN?1??, ynxn?A?3? yn取N?Max(N1,N2,N3),则对于???0,?N?0,n?N时,?3??所以: limxn?An??yn12.利用Stolz定理求下列极限a?2a2???nan(1)lim1,其中liman?a.2n??nn??解:令un?a1?2a2???nan,vn?n2,则un?1?un(n?1)an?1(n?1)an?1a?lim?lim?,n??vn?1?vnn??(n?1)2?n2n??2n?12lima?2a2???nana所以
lim1?.n??n221m?2m???nm(2)lim,m为正整数.n??nm?1解:1m?2m???nm(n?1)mlim?limn??n??(n?1)m?1?nm?1nm?1(n?1)m?limn??(m?1)mm?1(m?1)nm?n???121?.m?1?2?2(3)lim?2?n??2?1??11?2?2??23?1????122n?2?2????2n?1??. ??1n?112?2?2n?1?2?2?解:令an??2??3???2?1??2?1??2????2n?1??,则 ??n?1121?2222n?1?n?2?, lnan?n?1?ln2?2ln3???2lnn??2?2?12?12?1?所以2n?12lnn2n?11?limlnan?limn?1?limln?ln,n??n??2n??2?2n?22n?1n?2?2?2从而 lim?2?n??2?1??1n?11?2?2??23?1????2n?2?2?1?. ????2n?1?2??n?11213.设??k?, 证明数列{sinn?}发散.证明:因为??k?, 所以sin??0,cos??1. 假设数列{sinn?}收敛,记limsinn??A.n??则limsin(n?1)??A.n??展开:lim(sinn?cos??cosn?sin?)?A. 所以数列{cosn?}也收敛.n??记limcosn??B, 则Acos??Bsin??A, 即A(1?cos?)?Bsin?.?(1)n??再将cos(n?1)?展开:cosn?cos??sinn?sin??B. 两边取极限:Bcos??Asin??B, 即 ?Asin??B(1?cos?).?(2)(1)?sin??(2)?(1?cos?):0?B(sin2??(1?cos?)2)?2B(1?cos?).1(cos?)0,??0.从而有 B?0. 代入(1),A22A?在恒等式sinn??cosn??1 两边取极限:A2?B2?1,0?1, 矛盾! 14.已知?m,n0?xm?n?xm?xn,证明limxn存在.n??nxnx?x1,所以数列{n有nn证明:0?xn?x1?xn?1?x1?x1?xn?2???nx1,所以?n0?xnx}.下面证明limn?A.n??nnx因为A是下界,所以?nn?A.n界.记A?inf{???0,因为A是下确界,所以?N1当n?N1时,记n?qN1?r,xN1?A?. N12?0?r?N1,记x0?0. 则xn?xqN1?r?qxN1?xr,xnqxN1xr??. nnna??. n2记a?max(x1,?,xN1?1). ?N2?n?N2令N?max(N1,N2), 则 ?n?N有xnqxN1xrqxN1a???????A???A??. nnnqN1n22
范文三:微 积 分 练 习 题 答 案第一章
练习题答案(A)1. D
5. D 6. (1) (?4,4),
(2) (??,??).7. (1) f(0)?1, f(1)??1, f(?1)?3, f(1.5)?3.25, f(?1.5)?3.25.1(2) f(0)??, f(1)?0, f(?1)?0, f(1.5)?0.625, f(?1.5)?0.625.2?4x?5,8.(1)f(x)???2x?5,?1,??x(3)f(x)????1,??x2?x?5?x?9,,
(2)f(x)??2x?5??9?x,x?3x?3,x?0.x?0?x2?2x?2,x?29. f(x?1)??.2(x?1),x?2?10. (1) y?1(1?ex),D(f?1)?(0,??) . 2(2) y?9?x2,
D(f?1)?[0,3].
(3) y?3arccosx,
D(f?1)?[1,2]. 2?(x?1)2?(x?1),x??111. f(x?1)??,x??1?2,?x2?2x?2,?f(x)?f(?x)??0,?x2?2x?2,?x?0x?0. x?00?x?50?ax,12. 至少生产400套.
13. R(x)??.?50a?0.8a(x?50),x?5014. R(P)?12P?P,
15. y?x. 2x16. ?(x)?2x2?3是偶函数,?(x)?6x是奇函数. 17. (1) y?x3?1,
(2) y?(3)y?数相同1xx18. (1) y?arcsin,
(2) y?ex?1?2,
(3) y?log2.321?x1?x, 1?x?dx?b, 当a?d?0, 或b?c?0,a?d?0时,反函数与直接函cx?a19. (1) [-1,1] ,
(2) [2n?,(2n?1)?],(n?0,?1,?),
(3)[?a,1?a],(4) 若0?a?1,则定义域是[a,1?a],若a?0,则函数无定义. 2?1,?20. f[g(x)]??0,??1,?x?0?e,??x?0,
g[f(x)]??1,??1x?0??e,x?1x?1, 图略.
x?10?x?50?0.15x,21. y??,
图略.7.5?0.25(x?50),x?50?22. f[g(x)]为偶函数, g[f(x)]为偶函数, f[f(x)]为奇函数. 23.f{f[f(x)]}?(B)x1]?1?x. , f[x?1f(x)x?0?0,1. f(x)?f(?x)??.??2,x?02.(1)y?ln(x?x2?1), D(f?1)?(??,??)?x?1,(2)y???x,x??1x?0,
D(f?1)?(??,?1)?[0,??)?1?(x?1),?1?x?1(3)y??2,
D(f?1)?(?1,2).?2?2?x,1?x?2??f(x)?x3. f?.
?f(x)??f(x)?11?x??4.(1)f(x)?1x?1?(x)?,
(2).x?1x2?25. g(x)?ln(1?x),
D(g)?(??,0].6. (1) y?arccosu,u?x,
(2) y?lnu,u?v2,v?sinx, (3) y?eu,u?xlnx,
(4) y?arctanu,u?ev,v?x, (5) y?,u?x2.7. (1) 不可以,
(3) 不可以,
(4) 可以 8. 提示:参阅 (A) 第22题.
10. 略. 11. (1) D(f)?(??,??), Z(f)?Z,(整数集),?4?x,4?x?5(2) f(x)??,
12. 略.?5?x,5?x?6??1,13. f[g(x)]????0,??1,,
g[f(x)]???x?1,或x??2,1?x?x?1x?1.14. f(x)?x2?2,
g(x)?x2?2.111115. 提示:f(?a)?f(?a)?f()?f(?)?0.
16. 略3333
范文四:《微积分(1)》练习题一.单项选择题1.设f??x0?存在,则下列等式成立的有(
)f?x0??x??f?x0??f??x0?
B.limf?x0??x??f?x0???f??x0?A. lim?x?0?x?x?0?xC.limf?x0?2h??f?x0?f?x0?2h??f?x0?h?f?h?0?x0?
D.limh?1h?02f??x0?2.下列极限不存在的有(
) 2A.limxsin1x?0x2B.limx?2xx???x?11?3x2C. limex
?1?3x?0D.limx??2x6?x3.设f(x)的一个原函数是e?2x,则f(x)?(
)A.?2e?2x
D. ?2xe?2x?0?x?14.函数f(x)??2x,?1,x?1在?0,???上的间断点x?1为(
)间断点。??1?x,x?1A.跳跃间断点;
B.无穷间断点; C.可去间断点;
D.振荡间断点5. 设函数f?x?在?a,b?上有定义,在?a,b?内可导,则下列结论成立的有(
) A. 当f?a?f?b??0时,至少存在一点???a,b?,使f????0; B. 对任何???a,b?,有lim?f?x??f?????0;x??C. 当f?a??f?b?时,至少存在一点???a,b?,使f?????0; D.至少存在一点???a,b?,使f?b??f?a??f?????b?a?; 6. 已知f?x?的导数在x?a处连续,若limf??x?x?a??1,则下列结论成立的有(
x?aA.x?a是f?x?的极小值点;
B.x?a是f?x?的极大值点;)C.?a,f?a??是曲线y?f?x?的拐点;D.x?a不是f?x?的极值点,?a,f?a??也不是曲线y?f?x?的拐点;
二.填空: 1.设y?f?arcsin??1??,fx?可微,则y??x??2.若y?3x5?2x2?x?3,则y?6??3.过原点?0,1?作曲线y?e2x的切线,则切线方程为 4.曲线y?4?x?1?x2?2的水平渐近线方程为
铅垂渐近线方程为5.设f?(lnx)?1?x,则f??x??f?x??三.计算题:(1)limx?1x?2x?322x?1?x?2?(2)lim??x???x?x?3(3)lim (5)exyln(1?x)xsin3x2x?0(4)y??ln?1?2x??
求dy2?y?5x?0
求3dydxx?0x?0x?0四.试确定a,b,使函数f?x?????b?1?sinx??a?2,eax?1,在x?0处连续且可导。五.试证明不等式:当x?1时,e?x?e?六.设F?x??f?x??f?a?x?a,x12?xex?e??x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在且大于零,求证F?x?在?a,???内单调递增。《微积分》练习题参考答案一.单项选择题 1.( B
)2.( C )3.( A
)4.( C ) 5.( B )6.( B ) 二.填空:(每小题3分,共15分) 1. ?1f???arcsin1?? xx2?1?x?2. y?6??0 3. y?2x?1 4. y??2 , x?05. f??x??1?ex,f?x??x?ex?c三,计算题:(1)limx2?1x?1x2?2x?32limx?1x?1x2?2x?3?lim2xx?12x?2?12(3)limln(1?x2)x?0xsin3x2limln(1?x)x?0xsin3x
?limx2x?0x?3x?13(5)exy?y3?5x?0
求dydxx?0exy?y?xy???3y2y??5?0?y??5?yexy
3y2?xexy又x?0?y??1xyy?x?0?5?ye3y2?xexyx?0?2y??1x?3(2)lim?x?2?x????x??x?3l?x?2?x?im???x??2?x?l2????2???x??x?3?x?im?(1?x)?elim?2x?6x??x?e?2(4)y??ln?1?2x??2求dydy?2?ln?1?2x???11?2x???2?dx??4?ln?1?2x??1?2xdx(三.试确定a,b,使函数f?x?????b?1?sinx??a?2,eaxx?0x?0?1,在x?0处连续且可导。(8分)解:f?0?0??lim?b?1?sinx??a?2??a?b?2x?0?f?0?0??lim?ex?0?ax?1?0,
函数f?x?在x?0处连续f?0?0??f?0?0??a?b?2?0,
(1)?b?1?sinx??a?2???b?a?2?f???0??lim??bx?0xf???0??lim?x?0eax?1??a?b?2?x?limeax?1xx?0?a函数f?x?在x?0处可导f???0??f???0?,故a?b
(2) 由(1)(2)知a?b??1四.试证明不等式:当x?1时,e?x?e?tx12?xex?e
(8分)?证:(法一)设f?t??e
则由拉格朗日中值定理有e?x?1??e?e?ex??x?1??ex?x?1?
???1,x?整理得:e?x?e?xx12?xex?e?法二:设f?x??e?exxf??x??e?e?0?x?1?
故f?x??e?ex在x?1时,为增函数,xxf?x??e?ex?f?1??0,即ex?ex设f?x??e?xxf??x??e?12?xexx?ex?12?e?xe??12e?1?x??0x?x?1?
故f?x??e?x12?xex?e?在x?1时,为减函数,1x1xxxf?x??e??e?xe??f?1??0,即e??xe221xx综上,e?x?e??xe?e?2x?e?五.设F?x??f?x??f?a??x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在x?a且大于零,求证F?x?在?a,???内单调递增。
(5分) 证:F??x??f??x??x?a???f?x??f?a??(x?a)2?f??x??x?a??f?????x?a?(x?a)2?a???x??f??x??f????x?a?f??????x???x?a?0?????x?故F?x?在?a,???内单调递增。
范文五:一、填空题f(x0?3?x)?f(x0)?
?3A?x?0?x2.函数f?x??xx在点x?0处的导数f'?0??
01.设f'(x0)?A,则lim3.根据导数定义,函数f?x??xx?在点x?1处的导数f'?1??
不存在 4.函数f?x??sinx在点x?0处的导数f'?0??
不存在 5.设函数f(x)?(x?1)(x?2)(x?3)?(x?n)(其中n为正整数),则f'(0)?1↑ ?kk?127.设f?x??x2,则f'?f?x???
2xf(x0)?f(x0?2h)?3,则dy|x?x0?
?9dx 8.设y?f(x),且limh?06h9.y?x2?e?x,则y6.曲线y??1?x?e在点x?0处的切线方程为y?
n!xnd2y?1?10.设x?a(t?sint),y?a(1?cost),则
dx2a(1?cost)211arcsinx?)dx 11.设0?x?1,则d(xarcsinx)?
(2x2?x?x?1?t212.求曲线?在t?2处的切线方程
y?8?3(x?5) 3?y?t113.设y?2x?1,则其反函数x?x(y)的导数x?(y)?2dy12arctan4 14.设y?x?1)?arctan2x,则导数在点x?4处的值为
?dx417115.设需求函数Q?a?bP,则边际收益R'?Q??
?a?2Q?b516.某商品的需求量Q与价格P的关系为Q?P,则需求量Q对价格P的弹性是17.设某商品的需求函数为Q?1000?2P,其中P为价格,Q为需求量,则该商品的收ER1000?2Q?
益弹性1000?QEQ18.某商品的需求函数为Q?1000?2P,其中P为价格,Q为需求量,则销售该商品的a?2bP边际收益为R'?Q??
500?Qa?bPER?
19.某商品的需求量Q与价格P之间的关系为Q?a?bP,则该商品的收益弹性EP二、单项选择题f(x0?h)?f(x0)?1,则f'(x0)为
④ 1.设f(x)是可导函数,且limh?02h①1
④-2 2.设f(x)在x?1处可导,且f'(1)?2,则limf(1?x)?f(1?x)?
④33.函数f?x??x在x?0处满足下列哪个结论④3①极限不存在
②极限存在,不连续
③连续,不可导
④可导4.函数f?x?在区间?a,b?内连续是f?x?在?a,b?内可导的
①充分但非必要条件
②必要但非充分条件
③充分必要条件
④既非充分又非必要条件5.设f(x)为奇函数,则其导数f?(x)的奇偶性为
③非奇非偶
④奇偶性不定6.设函数f(x)可导,记g(x)?f(x)?f(?x),则导数g'?x?为
③非奇非偶
④奇偶性不定1,则当?x?0,该函数在点x?x0处的微分dy是② 2①与?x等价的无穷小
②与?x同阶的无穷小,但不等价
③与?x低阶的无穷小
④与?x高阶的无穷小?xx?0?8.函数f(x)??1?e1,在x?0处② x?x?0?0①不连续
②连续但不可导
③可导,且f'(0)?0
④可导,且f'(0)?1 9.设f(x)?xlnx在x0处可导,且f?(x0)?2,则f(x0)?
②7.设函数y?f(x)有f'(x0)?①0
④e 10.设e①e2x2x2为f(x)的导函数,则f??(x)?
④011.设f?(0)?2,则当x?0时,f(x)?f(0)是x的
② ①低阶无穷小量
②同阶无穷小量
③高阶无穷小量
④等价无穷小量三、求下列导数或微分dy1.设y?x?x?x,求
(dx2.设y??1?2x??1??2x?x?x?2x?x1??) ??xsindy11111,求
() sin?cosdxxx2xx2x3.y?ex?sinx?cosx?,求4.y?x?sinlnx?coslnx?,求dy(2coslnxdx) 5.y??x2,求dy(6.设y?3?x?xx3sin3xy'x?0(=2)xdxx?x2)sin3x??) x?1127.设y?x?arctan?ln?x,求y'
(arctan)xx?11?x?1?x?18.设y?(x?1),求dy((x?1?x?1)? ????dx)x?1?x?1?2x?12x?1?9.设f(x)?x(x?1)(x?2)?(x?100),求f?(0)
(=100!),求y?
(y??3xln3?3x2?xsin3x?3cos3xlnx???xsinxsinx?xcosx?x2cosx10.设y?,求dy
(dx) 21?x(1?x)dyxexexx2?ex11.y?,求
()x2dxx?exx?e??x?13x2112.设y?arctan((|x|?1),求y?
() x?2)?ln?x?11?(x3?2)2x2?16x2??613.设y?x6(x2?1)3(x?2)2,求y?
(x6(x2?1)3(x?2)??2??)xx?2x?1??314.设y?(x?1)2x?2(x?2)2(x?1)2x?2?212?,求y?
(???x?14(x?2)3(x?2)?) 2??(x?2)1x1?lnx) 2x2xsinx?2sinx?22sinx16.设y?(1?x),求dy
((1?x)cosxln(1?x)?dx) 2??1?x??2x?y(x2?y2)exy22xy17.由ln(x?y)?e?1确定y是x的函数y(x),求y?(x)y??? 22xy2y?x(x?y)e15.设y?x(x?0),求y?
(x?1xyex?ey18.已知ye?xe,求y'
(y)xe?exy?y?xlny?xy19.已知y?x,求y'
()xx?ylnx220.已知y?cot(x?y),求y'
(sec(x?y))121.已知y?ln?y?x??0,求y'
()y?x?1xy22.由ex2?y2?sin(xy)?5确定y是x的函数y(x),求y'(x)y'??2xex2ye2?y2?ycos(xy)?xcos(xy)x2?y223.设函数y?y(x)由方程ln(y?x2)?x3y?sinx确定,求dy(=1) dxx?0dy1?y224.设方程x?y?arctany?0确定了y?y(x),求
(y??) 2dxyay?x225.求由方程x?y?3axy?0(a?0)确定的隐函数y?y(x)的微分dy2dxy?axy26.已知y(x)是由方程siny?xe?0所确家的隐函数,求y?,以及该方程所表示的曲线33ey在点(0,0)处切线的斜率。
(?,?1)cosy?xeyf?27.设y?y(x)由方程y?f[x?g(y)]所确定,其中f和g均可导,求y?()1?f??g?d2y28.函数y?y(x)由方程e?e?xy?0确定,求dx2xyxyx?0[解]
对方程两边关于x求导,得e?ey??y?xy??0,两边关于x再求导,得ex?eyy?2?eyy???y??y??xy???0d2y又当x?0时,y?0,于是y?(0)?1,故dx2??2x?0?x?e2tcos2tdysin2t?sint?cost29.设?,求
() 22t2dxy?esintcost?sint?cost?30.设y?y(x)由x?(1?s)212和?s2dy) y?(1?s)所确定,试求(?2dx?s122?x?ecos2tdy31.设?,求
(=-1) 2dxy?esint??x?etcost2dyet(2sint?cost)32.设?,求
() 222tdxy?esintcost?2tsint??x?e2tdy3t?033.若参数方程为?,求在时的值。
() 2dx2?y?t?3t?2?x?2sin3td2yet(cos3t?3sin3t)34.设?,求
() t3236cos3tdx?y?e?ln2?x?e?td2y35.设?,求
((3?2t)e3t) t2dx?y?te?x?e2t1?4t3?5td2y?e?e) 36.设?,求
(?t224dx?y?t?e?x?t?sint?2d2y37.设曲线方程为?,求此曲线在点x?2处的切线方程,及 2dx?y?t?cost[解]
当x?2时,t?0,y?1,dy1?sintdy1?,?, dx1?costdxt?021d2yd?dy?1sint?cost?1???
切线方程:y?1?(x?2); ??2dx2dt?dx?dx(1?cost)3dt38.设y?(1?x)(2?3x)2(4?5x)3,求y(5)(0)
(=63900) 四、应用题1. 设生产某商品的固定成本为20000元,每生产一个单位产品,成本增加100元,总收益12x(假设产销平衡),试求边际成本、边际收益及边际利润。 2(C?(x)?100,R?(x)?400?x,L?(x)?300?x)42. 一人以2m/秒的速度通过一座高20m的桥,此人的正下方有一小船以m/秒的速度与桥3函数为R(x)?400x?垂直的方向前进,求第5秒末人与船相离的速率。 [解]
设在时刻t人与船的距离为s,则1?4?s?202?(2t)2??t??,3?3?2ds52tds26(m/s) ??2dt33600?5tdtt?52126答:第5秒末人与船相离的速率为(m/s)21五、分析题1. 设曲线f(x)在[0,1]上可导,且y?f(sin2x)?f(cos2x),求
(y??[f?(sin2x)?f?(cos2x)]sin2x)2. 设曲线方程为x3?y3?(x?1)cos(?y)?9?0,试求此曲线在横坐标为x??1的点处的切线方程和法线方程。
(y?2??(x?1),y?2?3(x?1)) 3. 设f(x)?3|a?x|,求f?(x)dy dx13??3a?xln3x?a(f?(x)??x?a,且f(x)在点x?a处不可导)?3ln3x?a?sinxx?04. 讨论函数f(x)??在x?0处的可导性。x?1x?0?(f(x)在x?0处不连续,不可导)?k?ln(1?x)x?05. 设f(x)??,当k为何值时,点x?0处可导;此时求出f?(x)。 sinxx?0?e1?x?0?(当k?1时,f(x)在点x?0处可导;此时f?(x)??1?x)sinx??ecosxx?0f(x)6. 若y?f(x)是奇函数且在点x?0处可导,则点x?0是函数F(x)?什么类型的x间断点?说明理由。 [解]
由f(x)是奇函数,且在点x?0处可导,知f(x)在点x?0处连续,f(0)??f(0),则f(0)?0,于是limF(x)?limx?0x?0f(x)?f(0)?f?(0)存在,x?0故点x?0是函数F(x)第一类间断点(可去)。?2ex?ax?07. 试确定常数a,b的值,使得函数f(x)??2处处可导。?x?bx?1x?0f(x)?limf(x)?f(0),即 [解]
为使f(x)在点x?0处连续,必须lim??x?0x?0x?0?limf(x)?2?a,limf(x)?f(0)?1,所以a??1, ?x?0?(0)?f??(0),即 为使f(x)在点x?0处可导,必须f?f(x)?f(0)2(ex?1)f??(0)?lim?lim?2, ?x?0?x?0x?0xf(x)?f(0)x2?bxf??(0)?lim?lim?b,所以b?2x?0?x?0?x?0x2?x??t3dy?2?0
8. 验证?(?1?t?1),满足方程y2dx?y??tdydy?t[解]
,????2dxdx?t2(?t?t1)???2(1?t)32223dy?2?0。
??3,即ydx2y2?t?x2x?19. 已知函数f(x)??在(??,??)上可导,求a和b的值。?ax?bx?1f(x)?limf(x)?f(1),即 [解]
为使f(x)在点x?1处连续,必须lim??x?1x?1x?1?limf(x)?1?f(1),limf(x)?a?b,于是a?b?1, ?x?1?(1)?f??(1),即 为使f(x)在点x?1处可导,必须f?f(x)?f(1)x2?1f??(1)?lim?lim?2,x?1?x?1?x?1x?1f(x)?f(1)ax?b?1f??(1)?lim?lim?a,于是a?2 ?x?1?x?0x?1x?1故a?2,b??1 六、证明题??x?1?x?01.证明函数f(x)??在点x?0处连续,但不可导。 x?0x?0?f(x)?0,lim[解]
f(0)?0,limf(x)?lim???x?0?x?1xx?0x?0?0,即limf(x)?f(0),所以f(x)在x?0处连续。x?0又因为f??(0)?lim?x?0f(x)?f(0)?x?1?lim?limx?0?x?0?x?0xx1x(1?x)??所以f(x)在x?0处不可导。2.设f(x)?g(x)sin?(x?x0)(??1),其中g(x)在x0处连续,证明:f(x)在x0处可导。f(x)?f(x0)g(x)sin?(x?x0)[证]
?lim ?limx?x0x?x0x?x0x?x0?lim?[g(x)sin??1(x?x0)]?x?x0??sin(x?x0)??g(x0)??1?????1x?x0??0?f(x)在x0处可导。
范文六:《微积分(1)》练习题一.单项选择题1.设f??x0?存在,则下列等式成立的有(
)f?x0??x??f?x0??f??x0?
B.limf?x0??x??f?x0???f??x0?A. lim?x?0?x?x?0?xC.limf?x0?2h??f?x0??f?x
D.limf?x0?2h??f?x0?h?1h?0h?0?
h?02f??x0? 2.下列极限不存在的有(
) 2A.limxsin1
B.x?0x2limx?2xx?1x???12C. limex
D.lim?3x?1?3x?0x??2x6?x3.设f(x)的一个原函数是e?2x,则f(x)?(
)A.?2e?2x
D. ?2xe?2x?4.函数f(x)??2x,0?x?1?1,x?1在?0,???上的间断点x?1为(
)间断点。??1?x,x?1A.跳跃间断点;
B.无穷间断点;C.可去间断点;
D.振荡间断点5. 设函数f?x?在?a,b?上有定义,在?a,b?内可导,则下列结论成立的有(
) A. 当f?a?f?b??0时,至少存在一点???a,b?,使f????0; B. 对任何???a,b?,有lim?f?x??f?????0;x??C. 当f?a??f?b?时,至少存在一点???a,b?,使f?????0; D.至少存在一点???a,b?,使f?b??f?a??f?????b?a?; 6. 已知f?x?的导数在x?a处连续,若limf??x?x?a??1,则下列结论成立的有(
x?aA.x?a是f?x?的极小值点;
B.x?a是f?x?的极大值点;
C.?a,f?a??是曲线y?f?x?的拐点;1)D.x?a不是f?x?的极值点,?a,f?a??也不是曲线y?f?x?的拐点;
二.填空: 1.设y?f?arcsin??1??,f可微,则y??x??
x?2.若y?3x5?2x2?x?3,则y?6??3.过原点?0,1?作曲线y?e2x的切线,则切线方程为
4.曲线y?4?x?1?x2?2的水平渐近线方程为铅垂渐近线方程为5.设f?(lnx)?1?x,则f??x??
三.计算题:?x?2?(1)lim2
(2)lim??x?1xx???2x?3x??x?12x?3(3)lim (5)exyln(1?x)xsin3x2x?0(4)y??ln?1?2x??
求dy2?y?5x?0
求3dydxx?0x?0x?0?b?1?sinx??a?2,四.试确定a,b,使函数f?x???axe?1,?在x?0处连续且可导。x五.试证明不等式:当x?1时,e?x?e?12?xex?e?六.设F?x??f?x??f?a?x?a,?x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在且大于零,求证F?x?在?a,???内单调递增。2《微积分》练习题参考答案一.单项选择题 1.( B
)2.( C )3.( A
)4.( C ) 5.( B )6.( B ) 二.填空:(每小题3分,共15分) 1. ?1f???arcsin1?? xx2?1?x?2. y?6??0 3. y?2x?1 4. y??2 , x?05. f??x??1?ex,f?x??x?ex?c三,计算题:(1)limx2?1x2?2x?3
x?1x2lim?1x?1x2?2x?3?lim2x2x?2x?1?12(3)limln(1?x2)xsin3xx?02limln(1?x)x?0xsin3x
?limx2x?0x?3x?13(5)exy?y3?5x?0
求dydxx?0exy?y?xy???3y2y??5?0y??5?yexy?3y2?xexy又x?0?y??1x?3(2)lim??x?2?x???x??x?3lim?x?2x?????x????lim(2x?22??????x??x?3?x??1?x)?elim?2x?6x??x?e?2(4)y??ln?1?2x??2求dydy?2?ln?1?2x???11?2x???2?dx??4?ln?1?2x??1?2xdx3y?(x?0?5?ye2xyxyx?0y??13y?xe?2?b?1?sinx??a?2,三.试确定a,b,使函数f?x???axe?1,?x?0x?0在x?0处连续且可导。(8分)解:f?0?0??lim?b?1?sinx??a?2??a?b?2x?0?f?0?0??lim?ex?0?ax?1?0,
函数f?x?在x?0处连续f?0?0??f?0?0??a?b?2?0,
(1)?b?1?sinx??a?2???b?a?2?f???0??lim??bx?0xf???0??lim?x?0eax?1??a?b?2?x?limeax?1xx?0?a函数f?x?在x?0处可导f???0??f???0?,故a?b
(2) 由(1)(2)知a?b??1x四.试证明不等式:当x?1时,e?x?e?12?xex?e
(8分)?证:(法一)设f?t??et
则由拉格朗日中值定理有e?x?1??e?e?ex??x?1??ex?x?1?
???1,x?整理得:e?x?e?xx12?xex?e?法二:设f?x??e?exxf??x??e?e?0?xx?1?
故f?x??e?ex在x?1时,为增函数,f?x??e?ex?f?1??0,即e?exxx设f?x??e?xxf??x??e?12?xexx?ex?1212?e?ex?xe??12e?1?x??0x?x12?1?
故f?x??e?x12?xex?e?在x?1时,为减函数, f?x??e?x?xex??f?1??0,即ex??xex?e?4综上,e?x?ex?五.设F?x??12?xex?e?f?x??f?a??x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在x?a且大于零,求证F?x?在?a,???内单调递增。
(5分) 证:F??x??f??x??x?a???f?x??f?a??(x?a)2?f??x??x?a??f?????x?a?(x?a)2?a???x??f??x??f????x?a?f??????x???x?a?0?????x?故F?x?在?a,???内单调递增。5《微积分(1)》练习题一.单项选择题1.设f??x0?存在,则下列等式成立的有(
)f?x0??x??f?x0??f??x0?
B.limf?x0??x??f?x0???f??x0?A. lim?x?0?x?x?0?xC.limf?x0?2h??f?x0??f?x
D.limf?x0?2h??f?x0?h?1h?0h?0?
h?02f??x0? 2.下列极限不存在的有(
) 2A.limxsin1
B.x?0x2limx?2xx?1x???12C. limex
D.lim?3x?1?3x?0x??2x6?x3.设f(x)的一个原函数是e?2x,则f(x)?(
)A.?2e?2x
D. ?2xe?2x?4.函数f(x)??2x,0?x?1?1,x?1在?0,???上的间断点x?1为(
)间断点。??1?x,x?1A.跳跃间断点;
B.无穷间断点;C.可去间断点;
D.振荡间断点5. 设函数f?x?在?a,b?上有定义,在?a,b?内可导,则下列结论成立的有(
) A. 当f?a?f?b??0时,至少存在一点???a,b?,使f????0; B. 对任何???a,b?,有lim?f?x??f?????0;x??C. 当f?a??f?b?时,至少存在一点???a,b?,使f?????0; D.至少存在一点???a,b?,使f?b??f?a??f?????b?a?; 6. 已知f?x?的导数在x?a处连续,若limf??x?x?a??1,则下列结论成立的有(
x?aA.x?a是f?x?的极小值点;
B.x?a是f?x?的极大值点;
C.?a,f?a??是曲线y?f?x?的拐点;1)D.x?a不是f?x?的极值点,?a,f?a??也不是曲线y?f?x?的拐点;
二.填空: 1.设y?f?arcsin??1??,f可微,则y??x??
x?2.若y?3x5?2x2?x?3,则y?6??3.过原点?0,1?作曲线y?e2x的切线,则切线方程为
4.曲线y?4?x?1?x2?2的水平渐近线方程为铅垂渐近线方程为5.设f?(lnx)?1?x,则f??x??
三.计算题:?x?2?(1)lim2
(2)lim??x?1xx???2x?3x??x?12x?3(3)lim (5)exyln(1?x)xsin3x2x?0(4)y??ln?1?2x??
求dy2?y?5x?0
求3dydxx?0x?0x?0?b?1?sinx??a?2,四.试确定a,b,使函数f?x???axe?1,?在x?0处连续且可导。x五.试证明不等式:当x?1时,e?x?e?12?xex?e?六.设F?x??f?x??f?a?x?a,?x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在且大于零,求证F?x?在?a,???内单调递增。2《微积分》练习题参考答案一.单项选择题 1.( B
)2.( C )3.( A
)4.( C ) 5.( B )6.( B ) 二.填空:(每小题3分,共15分) 1. ?1f???arcsin1?? xx2?1?x?2. y?6??0 3. y?2x?1 4. y??2 , x?05. f??x??1?ex,f?x??x?ex?c三,计算题:(1)limx2?1x2?2x?3
x?1x2lim?1x?1x2?2x?3?lim2x2x?2x?1?12(3)limln(1?x2)xsin3xx?02limln(1?x)x?0xsin3x
?limx2x?0x?3x?13(5)exy?y3?5x?0
求dydxx?0exy?y?xy???3y2y??5?0y??5?yexy?3y2?xexy又x?0?y??1x?3(2)lim??x?2?x???x??x?3lim?x?2x?????x????lim(2x?22??????x??x?3?x??1?x)?elim?2x?6x??x?e?2(4)y??ln?1?2x??2求dydy?2?ln?1?2x???11?2x???2?dx??4?ln?1?2x??1?2xdx3y?(x?0?5?ye2xyxyx?0y??13y?xe?2?b?1?sinx??a?2,三.试确定a,b,使函数f?x???axe?1,?x?0x?0在x?0处连续且可导。(8分)解:f?0?0??lim?b?1?sinx??a?2??a?b?2x?0?f?0?0??lim?ex?0?ax?1?0,
函数f?x?在x?0处连续f?0?0??f?0?0??a?b?2?0,
(1)?b?1?sinx??a?2???b?a?2?f???0??lim??bx?0xf???0??lim?x?0eax?1??a?b?2?x?limeax?1xx?0?a函数f?x?在x?0处可导f???0??f???0?,故a?b
(2) 由(1)(2)知a?b??1x四.试证明不等式:当x?1时,e?x?e?12?xex?e
(8分)?证:(法一)设f?t??et
则由拉格朗日中值定理有e?x?1??e?e?ex??x?1??ex?x?1?
???1,x?整理得:e?x?e?xx12?xex?e?法二:设f?x??e?exxf??x??e?e?0?xx?1?
故f?x??e?ex在x?1时,为增函数,f?x??e?ex?f?1??0,即e?exxx设f?x??e?xxf??x??e?12?xexx?ex?1212?e?ex?xe??12e?1?x??0x?x12?1?
故f?x??e?x12?xex?e?在x?1时,为减函数, f?x??e?x?xex??f?1??0,即ex??xex?e?4综上,e?x?ex?五.设F?x??12?xex?e?f?x??f?a??x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在x?a且大于零,求证F?x?在?a,???内单调递增。
(5分) 证:F??x??f??x??x?a???f?x??f?a??(x?a)2?f??x??x?a??f?????x?a?(x?a)2?a???x??f??x??f????x?a?f??????x???x?a?0?????x?故F?x?在?a,???内单调递增。5
范文七:《微积分(1)》练习题一.单项选择题1.设f??x0?存在,则下列等式成立的有(
) A. limf?x0??x??f?x0?f?x0??x??f?x0??f??x0?
B.lim??f??x0??x?0?x?x?0?xC.limf?x0?2h??f?x0?h?f??x
D.limf?x0?2h??f?x0?1h?00?h?0h?2f??x0?2.下列极限不存在的有(
)A.limx?0xsin1x2?2xx2
B.xlim???x?112C. limxx?0eD.lim?3x?1?3x??2x6?x3.设f(x)的一个原函数是e?2x,则f(x)?(
)A.?2e?2x
D. ?2xe?2x?4.函数f(x)??2x,0?x?1?1,x?1在?0,???上的间断点x?1为(
)间断点。??1?x,x?1A.跳跃间断点;
B.无穷间断点;C.可去间断点;
D.振荡间断点5. 设函数f?x?在?a,b?上有定义,在?a,b?内可导,则下列结论成立的有(
) A. 当f?a?f?b??0时,至少存在一点???a,b?,使f????0; B. 对任何???a,b?,有limx???f?x??f?????0;C. 当f?a??f?b?时,至少存在一点???a,b?,使f?????0; D.至少存在一点???a,b?,使f?b??f?a??f?????b?a?; 6. 已知f?x?的导数在x?a处连续,若limf??x?x?ax?a??1,则下列结论成立的有(
A.x?a是f?x?的极小值点;
B.x?a是f?x?的极大值点;1)C.?a,f?a??是曲线y?f?x?的拐点;D.x?a不是f?x?的极值点,?a,f?a??也不是曲线y?f?x?的拐点;
二.填空:1.设y?f?arcsin?,f可微,则y??x????1?x?2.若y?3x5?2x2?x?3,则y?6??3.过原点?0,1?作曲线y?e2x的切线,则切线方程为4?x?1??2的水平渐近线方程为x2铅垂渐近线方程为4.曲线y?5.设f?(lnx)?1?x,则f??x??f?x??三.计算题:x2?1?x?2?(1)lim2
(2)lim??x?1x?2x?3x???x?x?3ln(1?x2)2(3)lim
(4)y??ln?1?2x??
求dyx?0xsin3xxy3(5)e?y?5x?0
求dydxx?0四.试确定a,b,使函数f?x????b?1?sinx??a?2,x?0在x?0处连续且可导。
axe?1,x?0?1xex?e
2x五.试证明不等式:当x?1时,e?x?e???六.设F?x??f?x??f?a?,x?a?x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内存在且大于零,求证F?x?在?a,???内单调递增。2《微积分》练习题参考答案七.单项选择题 1.( B
)2.( C )3.( A
)4.( C ) 5.( B )6.( B ) 八.填空:(每小题3分,共15分) 1. ?1xx2?1f????arcsin1?x??2. y?6??0 3. y?2x?1 4. y??2 , x?05. f??x??1?ex,f?x??x?ex?c三,计算题:(1)limx2?1x?1x2?2x?3
2limx?1x?1x2?2x?3?lim2xx?12x?2
?123)limln(1?x2()x?0xsin3x
ln(1?x2lim) x?0xsin3x
?limx21x?0x?3x?3(5)exy?y3?5x?0
求dydxx?0exy?y?xy???3y2y??5?0?y??5?yexy3y2?xexy又x?0?y??1x?3(2)lim?x?2?x????x??x?3lim?x?2?x????x???lim2x??2???x?3?x??(1??2???x?x) 2x??exl?i??6x?e?2(4)y??ln?1?2x??2求dydy?2?ln?1?2x???1???2?dx
1?2x??4?ln?1?2x??1?2xdx3y?x?0(5?yexy?23y?xexyx?0y??1?2九.试确定a,b,使函数f?x???(8分)?b?1?sinx??a?2,x?0在x?0处连续且可导。
axe?1,x?0??b?1?sinx??a?2??a?b?2 解:f?0?0??lim?x?0axf?0?0??lime?1?0,
函数f?x?在x?0处连续f?0?0??f?0?0? ?x?0??a?b?2?0,
(1)?b?1?sinx??a?2???b?a?2??bf???0??limx?0?xeax?1??a?b?2?eax?1f???0??lim?lim?ax?0x?0?xx??0??f???0?,故a?b
(2) 函数f?x?在x?0处可导f?由(1)(2)知a?b??1x十.试证明不等式:当x?1时,e?x?e?1xex?e
(8分) 2??证:(法一)设f?t??e
则由拉格朗日中值定理有te?x?1??ex?e?e??x?1??ex?x?1?
???1,x?整理得:e?x?e?xx1xex?e 2??法二:设f?x??e?exf??x??ex?e?0?x?1?
故f?x??ex?ex在x?1时,为增函数,f?x??ex?ex?f?1??0,即ex?ex设f?x??e?x1xex?e 2??f??x??ex?1x1e?xex?ex?1?x??022???x?1?
故f?x??e?x1xex?e在2??x?1时,为减函数,11f?x??ex?ex?xex?f?1??0,即ex?xex?e22????4综上,e?x?e?十一. 设F?x??x1xex?e 2??f?x??f?a??x?a?,其中f?x?在?a,???上连续,f???x?在?a,???内x?a存在且大于零,求证F?x?在?a,???内单调递增。
(5分) 证:F??x??f??x??x?a???f?x??f?a??(x?a)2?f??x??x?a??f?????x?a?(x?a)2?a???x? ?f??x??f????x?a?f??????x???x?a?0?????x? 故F?x?在?a,???内单调递增。5
范文八:(2.4)7.证明方程x5?3x?1在1与2之间至少存在一个实根.证:设函数f(x)=x5?3x?1,则f(x)在?1,2?上连续,且f(1)?1?3?1??3?0f(2)=2?3?2?1?25?0,故f(1)?f(2)5所以存在??(1,2),使f(?)?0,而f(?)?0说明方程x5?3x?1在1与2之间有实根.8.设f(x)在?a,b?上连续,且f(a)?a,f(b)?b, 证明在区间(a,b)内至少存在一点?,使f(?)??. 证:设g(x)?续,又g(a)?f(a)?a?0 ,g(b)?f(b)?b?0, g(a)g(b)?00?f(x)?x,由于f(x)在?a,b?上连续,所以g(x)在?a,b?上连,故存在一点??(a,b),使g()?,即存在一点??(a,b),使f(?)??.习题二?15?设?x,f(x)???1,x?0x?0,则limf(x)?(x?0).?A?0
?D?不存在解:由题设,知limx?0所以应选?A?.?23?函数y?f(x)?limx?0x?0(x?1)(x?2)的间断点有( ).?A?1个
?D?0个解:根据题意得函数的定义域为[3,??) 所以函数的间断点为0个,故应选?D?.?3?n??lim1n[(x?an)?(x?2an)???(x?(n?1)ana])]=lim1nn??[(n?1)x?1?2???(n?1)n=lim[(1?n??1n1n)x?)x?1?2???(n?1)nn?12na]2a]=lim[(1?n??=x?.2a?4?x???limx?x?x?1x=xlim???301?11?x?1x20x=xlim???=1.?5?lim(2x?1)20(3x?2)50x??(2x?1)=lim(x??2x?12x?1)(3x?22x?1)30=120330?()2=(32)30.?6?n??lim2n?1n?3n?1n2?32n2()?3=lim?3n??2n()?13.4.已知lim(x??x?1x?12?ax?b)?3,求常数a,b.解:?lim(x???1?a?0,x?1x?12?ax?b)?lim(1?a)x?(a?b)x?1?bx?1a?1,b??42x???3 而x??,?(a?b)1?3从而9.给f(0)补充定义一个什么值,能使f(x)在x?0处连续??1?f(x)?sinxcos1xm?2?xcos1x1f(x)?ln(1?kx)x解:?1?函数f(x)?sin但由于limx?0x?0在点x?0处无定义,?0f(x)?limsinxcosx处连续.所以补充f(0)?0,则有limx?0mf(x)?f(0),可使f(x)在x?0?2?函数f(x)?ln(1?kx)x在点x?0处无定义,mmln(1?kx)但由于limx?0x?limln(1?kx)x?0kxk1?ln[lim(1?kx)x?0kx]km?km所以补充f(0)?km,可使f(x)在x?0处连续.10.设f(x)为连续函数,x?a与x?b是f(x)?0的两个相邻的根, 证明:若已知(a,b)内一点c,使f(c)?0(或?0),则f(x)在(a,b)内处处为正(或负).证明:(反证法)仅证处处为正(为负同理)
假设在(a,b)内存在一点d,使得f(d)?0
若f(d)?0,则与已知矛盾
若f(d)?0,又f(c)?0由零值定理知在(c,d)或(d,c)(?(a,b))内存在一点?,使得f(?)?0,即?是介于a,b之间的一个根, 这与a,b是相邻两根矛盾,故假设不成立.所以f(x)在(a,b)内处处为正.11.设f(x)与g(x)均在[a,b]上连续,且f(a)?g(a),f(b)?g(b),证明:在(a,b)内至少存在一点c,使得f(c)?证:设h?x??g(c).由于f(x)与g(x)均在[a,b]上连续,所以h(x)f(x)?g(x),在[a,b]上连续,又h(a)?f(a)?g(a)?0h(b)?f(b)?g(b)?0(f(a)?g(a)) (f(b)?g(b))f(c)?g(c)?0,由零值定理知:在(a,b)内至少存在一点c,使得h(c)?即在(a,b)内至少存在一点c,使得f(c)?(3.4)(4)求n阶导数:(4)y?a??a1x???anxng(c).y??a1?2a2x?3a3x???nanx2n?1n?2y???2a2?6a3x???n(n?1)xy????6a3??n(n?1)(n?2)anx?n?3y(n)?ann!习题三(3)已知1?a?xsin,x?0f(x)??x?0,x?0?在x?0处连续但不可导,则(C)(A)a?0
(C)0?a?1
(D)a?2?f(x)在x?0处连续∴lim?f(x)?lim?f(x)?f(0)?0x?0x?0?即x?0lim?xsin?1x?lim?0?0x?0只有limx?0x?0a ∴a?0sin1x?0∵f(x)在x?0处不可导,∴f??(0)?f??(0)?0xsin?lim?x?0a1x即limx?0f(x)?f(0)??0?lim?xx?0a?1x∴a?1?0,a?1于是0?a?1g(x)xx?0(6) 已知函数f(x),g(x)在x?0的某邻域内连续,且limlimf(x)g(x)2??1,x?0?2,则在点x?0处f(x)(B)?0)?0 (C)可导且f(?0)?0
(D)无法判断 (A)不可导 (B)可导且f(?limg(x)x2x?0??1,∴()型,而g(x)连续,因此limg(x)?0?g(0)x?002由limg(x)?[g(0)]?0,limx?0x?0?2,得此极限也是()型2g(x)0f(x)于是连续函数f(x)有limf(x)?f(0)?0,x?0∴limf(x)?f(0)x?0x?0?limf(x)xx?0f(x)g(x)?lim2g(x)?2?(?1)?0?0x?0g(x)x?0)?0 所以在点x?0处f(x)可导且f(7.(42)解:当x?1时,f?(x)?2xe?x?x2(?2x)e?x?2xe?x(1?x2)22当x?1时f?(x)?1??)e1?lim?ee?0x?1x?1?x2当x?1时x?1lim?f(x)?f(1)x?1xe?lim?x?12?1?x2(1?x)?0?f?(1)?0x?1lim?f(x)?f(1)x?1?10()0x?1?lim2xex?1?当x??1时x??1lim?f(x)?f(?1)x?11?1xe?lim?x??12?x2?1?0x?1x??1lim?f(x)?f(?1)x?1?lim??0∴f?(?1)?0x??1x?12?x2?|x|?1?2x(1?x)e∴f?(x)??|x|?1??015.在下列括号内填入适当的函数 (1)cdx(3)1x?d(cx?c)(2)x?dx?d(
(4)ax1??1axx??1?c)(???1)dx?d(lnx?c)dx?d(lna?c)(5)sin(7)secxdx?d(?cosx?c)2(6)cosxdx2?d(sinx?c)xdx?d(tanx?c)(8)cscxdx?d(?cotx?c)(9)secxtan(11xdx?d(secx?c)
(10)cscxcot
(12)11?x2xdx?d(?cscx?c)?d(arcsinx?c)dx?d(arctanx?c)16.设函数y?f(x)分别隐含在下列方程中,分别求其微分dy解:(1)方程两边同时对x求导2x?2y?y??y?xy?y??y?2x2y?x?dy?
?dy?y?2x2y?xy?2x2y?xdx或d(x2?y2)?dxy2xdx?2ydy?ydx?xdydx(2)两边同时对x求导ex?y(1?y?)?y?xy??0y??ex?y?yx?yx?e?1?xy?yx?1?xy?dy?1?xy?yx?1?xydx17.已知u,v是x的可微函数,求下列函数微分 解:(1)dy?d(
(2)dy?duv)?2vdu?udvv422?vdu?2uvdvv42?vdu?2udvv3?vu??2uv?v3dx??udu?vdv(u?v)2232??uu??vv?(u?v)222dx18.求下列各数的近似值 解:(1)设f(x)?sinxf?(x)?cosx
取x?30??6(??x??1???180f(x0??x)?f(x0)?f?(x0)?xsin29?sin11?x2?6?cos?6?180)?12?360(2)令f(x)?arctanxf?(x)?取x0?1?x?0.05f(x0??x)?f(x0)?f?(x0)?x11?12arctan1.05?arctan1??0.05??4?0.25(3)令f(x)?f?(x)?15x?45取x0?32
?x?1f(x0??x)?f(x0)?f?(x0)?x1618033?32?1551(32)4?1?4?
令f(x)?x10?2?180?99f?(x)?10x
取10x?110?x?0.01f(x0??x)?f(x0)?f?(x0)?x?9(1.01)?1?10?1?0.01?1?0.1?1.1?5?
令f(x)?1x10f?(x)?110x10取2x0?2Δx??24f(x0??x)?f(x0)?f?(x0)?x1?(2)10?10110(2)109?10?9?(?24)?2?10(?24)?1.996?6?
令f(x)?lnxf?(x)?1x取x3?e33?x??1f(x0??x)?f(x0)?f?(x0)?xln(e?1)?lne?1e3(?1)?3?1e3m?319. ?6? 当n?......y(n)m2时y??m(ax?b)m?2m?1a?ma(ax?b)3m?1y???m(m?1)a(ax?b)y????m(m?1)(m?2)a(ax?b)nm?n?m(m?1)(m?2)…(m?n?1)a(ax?b)y?n?当n?m时
?y20.y?y??nxn?1?0n?mn?m(n)?m(m?1)…(m?n?1)an(ax?b)m?n??0?x[C1cos(lnx)?C2sin(lnx)]n[C1cos(lnx)?C2sin(lnx)]?xn?2n?1[?C1sin(lnx)?C2cos(lnx)]n?2y???n(n?1)x?(n?1)x2[C1cos(lnx)?C2sin(lnx)]?nxn?2[?C1sin(lnx)?C2cos(lnx)]n?2[?C1sin(lnx)?C2cos(lnx)]?x2n2[C1cos(lnx)?C2sin(lnx)]xy???(1?2n)y??(1?n)y=x{(n?n?1)[C1cos(lnx)?C2sin(lnx)]?(2n?1)[C2cos(lnx)?C1sin(lnx)]}?(1?2n)x{n[C1cos(lnx)?C2sin(lnx)]?[Ccos(lnx)?Csin(lnx)]}?(1?n)x[C1cos(lnx)?C2sin(lnx)]?02nn
范文九:微积分上册本科复习题一班级:
.一、填空题 (本题共3小题,每小题4分,共12分. 把答案填在题中横线上)?1?x2,x?0?x2,x?0?1?x,x?01、 设函数f(x)??,?(x)??则f[?(x)]?f[?(x)]???1?x,x?0??x,x?02、 设 x1?10,xn?1?2?xn(n?1,2,?),则limn??xn? 23、函数f(x)?x2?2x?2的间断点为x?2 ;4、lim1x??xsinx?1xsin5x? 1 5.曲线yex?lny?1在点(0,1)处的切线方程为 y?1?0.5x6.当x??1时,函数y?x3?2px?q取得极值,则p? -1.57.若f(x)?x(x?1)(x?2)?(x?10),则f'(0)?10!8.函数y?lnx的拐点为(1,0)9.设y?1(n)(?1)nn!1?x ,则n阶导数y?(x?1)n?110.?exsinxdx? 12ex(sinx?cosx)?C二、选择题:(本题共5小题,每小题2分,共10分.)k1、设lim(1?x)xx?0?e2,则k?(A
D、0 2、方程ex?y?xy?1确定了函数y?f(x),f?(0)?(
D、?2?1?x,x?03、设函数y?f(tanx),其中f可导。则微分dy?(
) A.f?(tanx)dx C、B、sec2xf?(tanx)1f?(tan)dx
D、 sec2xf?(tanx)dx 21?xk4.若x?0时,2sinx?sin2x~x,则k?(
D. 4.5、 设函数f(x)在x?0处连续,下列命题错误的是:D (A) 若limx?0f(x)存在,则f(0)?0 x(B) 若limx?0f(x)?f(?x)存在,则f(0)?0xf(x)存在,则f?(0)存在 xf(x)?f(?x)存在,则f?(0)存在x(C) 若limx?0(D) 若limx?0三、计算题 (本题共8小题,共64分)1??1、求极限 lim?xtan?.x???x??x2x32、求极限 limx?0x?sinx3、求?1?x?x2'4.设y?xx(x?0),求y。5.?secxtan5xdx1?x??1
x?0,求f(x)的间断点,并说明间断点所属类型. 6、设f(x)??e,
??ln(1?x),
?1?x?0?7.求函数y?x?2cosx在[0,]上的最值。2?x2,
x?18、设函数f(x)??在x?1处可导,求常数a,b的值.?ax?b,
x?1四、证明题 (6分)证明方程x?cosx?0有且仅有一个实根。答案一、填空题 (本题共10小题,每小题2分,共20分.)?1?x2,x?01.f[?(x)]?? ; 2.
5.y?1?0.5x?1?x,x?01x(?1)nn!e(sinx?cosx)?C 6.?1.5
10.n?12(x?1)二、选择题:(本题共5小题,每小题2分,共10分.)1.A ;
D;三、计算题 (本题共8小题,共64分)1??1、求极限 lim?xtan?.x???x??1?tant?t2解:令t?, 极限化为 lim??,
--------------------2分 ?t?0x?t?1?tant?t2记y???,则lny?2?lntant?lnt?,
--------------4分t?t?sec2t1?1 ?limlimlny?limlntant?lnt??t?0?t?0?t?0?t22t111?t?sin2tt?sintcost?lim3?lim?lim2t?0t?0t?02tsintcost2t2t21?cos2t2t1?lim?lim?,
-------------- 6分 22t?0t?06t36t1x21所以 原极限?e.
------------------8分13x32、求极限 limx?0x?sinxx33x2?lim解:
limx?0x?sinxx?01?cosx----------- ---------3分6x---------------------6x?0sinx?6--------------------------------8分?lim3、求?解:?1?x?x1?x?x22x?x2?arcsinx??dx--------------------3分1d(1?x2)?arcsinx??dx-----------------6分22?x
?arcsinx??x2?C--------------------8分4.设y?x(x?0),求y。'解:两边取对数,得
lny?对上式两边关于x求导,得lnx--------------------3分 xy'1?lnx?
-------------------------6分yx21?lnx))
----------------------------------8分 所以y'?y(2x5.?secxtan5xdx解:
?secxtan5xdx??tan4xdsecx
---------------2分??(sec2x?1)2dsecx ---------------4分 ??(sec4x?2sec2x?1)dsecx --------6分12?sec5x?sec3x?secx?C
-------8分 531??e,
x?0,求f(x)的间断点,并说明间断点所属类型. 6、设f(x)????ln(1?x),
函数在x?1处无定义.e
?f(1?0)?lim?x?11x?1?0,
f(1?0)?lime?x?11x?1???,
(3分)?x?1是f(x)的第二类间断点.
又x?0为函数的分段点.ln1(?x)?0,
f(0?0)?lim
?f(0?0)?lime??x?01x?1x?0?e?1,
(7分)?x?0是f(x)的第一类间断点(跳跃间断点).
(8分)?7.求函数y?x?2cosx在[0,]上的最值。2??解:由y'?1?2sinx?0,知x?为函数在(0,)内的唯一驻点。---4分62????y()?,y()??,y(0)?2,
-----------------6分 2266????所以,最大值为y()??3,最小值为y()?。 ------------8分6622?x2,
x?18、设函数f(x)??在x?1处可导,求常数a,b的值.ax?b,
x?1?答:解
由f(x)在x?1可导知f(x)在该点必连续.(ax?b)?a?b. x2?1?f(1),
f(1?0)?lim
f(1?0)?lim??x?1x?1由f(1?0)?f(1?0)?f(1)得 a?b?1.
(3分)f(x)?f(1)x2?1?lim?2,
f??(1)?limx?1x?1?x?1?x?1f(x)?f(1)ax?b?1ax?af??(1)?lim?lim?lim?a.x?1x?1x?1?x?1?x?1?x?1由f??(1)?f??(1)得a?2.(2)(6分)解(1)、(2)得a?2,b??1.
(8分)四、证明题 (6分)证:设f(x)?x?cosx
v----------------------1分f(x)在区间[???,]上连续,f(?)f()?0 2222??由零点定理知,f(x)在(?而f'(x)?1?cosx?0,??,)上至少存在一个零点。
-------3分22所以f(x)在(??,??)上单调递增,故结论成立
------------------------6分
范文十:微积分复习解答一、 求极限?11.lim?n??n??4n?344?n1x21x1?limsin?limsin?0 2. limx?0ln(1?2x)x?02xxx?02xx2sin?sinxx2?sinxx22x23. lim??x??lim?limx?0?limx?limx?0x???x???ex???ex???ee?x???x?x4. limx?x???????arctanx??lim?2?x?????arctanxx12x2?lim?lim?1x???x???1?x2?2x?5.limx?01?sinx?1?tanx?1limsinx?tanx ?x?0x32x?0x31tanxcosx?111?x2?1?lim ??lim????22?x?0x?02xx2x?2?4sin2xln(1?3x)2x?3xx26. lim?lim?6lim2?6 sinxx?0x?0x?0xx(e?1)x?sinx17. lim(cosx)x?lim(1?cosx?1)x?0x?021cosx?1?cosx?1x2?ex?0limcosx?1x2?ex?0lim?x22x2?e?128. lim?1?sinx??lim?1?(?sinx)?x?0x?0xx1x1?sinx?sinxx?e?1xx?1?2xlim??2??x?1??x?1?1?1???2x???2x?19. lim? ?lim?lim1??e?e?x????x????x??x?1???x?1??x?1??10. limx?02x0ln(1?t)dt1?cosx2tanx?limln(1?2x)?2?4
(删去)x?0sinx二、 求下列函数的导数或微分1. 已知y?xe,求dytanx?x2etanxsec2xdx 解:dy?2xe??2. 设y?xarcsinx?ln2,求y? 3解:y??arcsinx?x3x??arcsin 33.y?y?,y??2x2?1x2(x2?1)321
解:y??y????21?x?14. 设y?5sinx??lnx2?,求dy ln2sinx解:y?5?2lnx
ln2xdydxy??5sinx?ln5?cosx?2f(x)?5. 设y?sin???,其中f有可导,求dy2222??????cos?f(x)?f(x)?2x?2xcosf(x)f(x) ????dxdyxy6.方程e?lny?y(x),求x?0dx解:解:将x?0代入上述方程,得:1?lny,y??e,
在方程两端同时对x求导:得ey?exy??xyxy12x?2yy?,2x2?y2代入x?0,y??e,得: ?e?y?(0)2,而y?(0)?e ?e7. 方程exy?1?x?y确定y?y(x),求y?(0)解:exy?1?x?y,代入x?0,得:e0?1?0?y(0),得:y(0)?0
在方程的两端同时对x求导:exy?y?xy???1?y?,代入x?0,y?0,得:0?1?y?(0),得:y?(0)??1 8.设arctanydy?ln xdxy?ln(x2?y2),
对x求导:2?x解:原式:2arctan1?y?1????x??2y?x?y2x?2yy?, ?222xx?y整理得y?x?y?x?yy?,解得:y??三、 求下列积分:1.x?yx?y?sin2解:原式=sinudu?sinu?2udu??2ud(cosu)??2ucosu?2cosudu????????2ucosu?2sinu?C??C 2.解:设 x?tant,则: 原式=?2x?2sec2tdt??1?sec2tdt??cos3tdt 5sectt? sCin)?1
?costd(sitn?(?)stind13(ts?in)sin31?33.x33?Cx?1?xlnxdx1ln2x?C 解:原式=?lnxdx??lnxdx?xlnx??dx??lnxd?lnx??xlnx?x?x24.?1?1(x2dx解:??1?1(x2dx??(x2?2(1?x2))dx??dx?2?1?1115.?4??4?2??x2sinx?cosxxsinxcosx?44?2arctan ??dx?0?2arctan(sinx)???222?0?1?sinx1?sinx?24?1?sinx???x2sinxcosx?4?2arctan解:原式=??? ?dx?0?2arctan(sinx)?220?1?sinx?24?1?sinx46.?21x2lnxdx2解:原式=?lnxd(x3)?x3lnx??x3?dx?ln2?x3?ln2?.?2?1xedxx解:?2?1xedx??xedx??xedx?0??xde?xe?12x1x2x2xx211??exdx?2e2?e?ex1122?2e?e?e?e?e 8.22???0e解:???0e??e?2udu??2?ude??2ue???u???u?u???2?e?udu?0?2e?u????0?29.?0?解:?0?30002???????(x?1)2???30??11?24?2?? 33四、 间断点及其类型判定,函数的连续性:x2?x1. 设f(x)? ,确定其间断点,并判定间断点类型。若是可去间断点,补充定义使其连续。x(x?1)解:间断点x?0,1f(x)?1,limf(x)??1, x?0为跳跃间断点
lim??x?0x?0(?),1x?1为可去间断点, 补充定义f(1)?1
limfxx?1?sinx,x?0?2. 设f(x)??x,(1).讨论f(x)在x?0处连续性,若间断,指出其类型;(2) 求f?(x)。??2x?1,x?0f(x)?limf(x)?1?f(0),f(x)在x?0处连续. 解.(1) lim??x?0x?0(2) 以下忽略? 1
f(0)f(x)?f(0)(2x?1)?1?lim?2?f??(0) ?x?0x?0xxsinx?1f(x)?f(0)sinx?x?
limlim?lim?0?f??(0) 2?x?0?x?0?x?0xxxlim?f??(0)?f??(0),函数在x?0不可导。?31?x2sin,x?03. 讨论函数f(x)??在x?0处的连续性和可导性。 x?0,x?0?解:limf(x)?0?f(0), 此函数在x?0处的连续。x?0以下讨论函数的可导性部分
略1f(x)?f(0)1?limx2sin?0?f?(0),此函数在x?0处可导.
limx?0x?0xx?ln(1?3x),x?0?4. 设f(x)??
确定a,b值,使f(x)连续且可导。 x?,x?0?ax?bf(x)?limf(x)?f(0),得b?3 解:由f(x)在x?0处连续, lim??x?0x?0由f(x)在x?0处可导, f??(0)?f??(0),得f(x)?x?0xf(x)?f??(0)?limx?0?xf??(0)?lim?ln(1?3x)3?3?3f(0)ln(1?3x)?3x9?limlim? ?lim??2??x?0x?0?x?0xx2x2f(0)9?a ,则a??2五、 不等式证明:x3?sinx?x1. x?6(x?0)证明:令g(x)?x?sinx,在区间(0,??)上连续,又g?(x)?1?cosx?0,且使g?(x)?0的点是孤立点,所以g(x)在[0,??)单调递增,
所以:当x?0时g(x)?g(0)?0,即 sinx?x.x3?sinx,在区间(0,??)上连续, 令f(x)?x?6x2x22x?cosx?2sin??0,所以f(x)在[0,??)单调递减,
又f?(x)?1?222x3?sinx
所以:当x?0时f(x)?f(0)?0,即
x?6综合上述所得,知结论成立。 2. ln(1?x)?xx?0 1?x证明:令f(x)?(1?x)ln(1?x)?x,定义域x??1,f?(x)?ln(1?x)当?1?x?0时,f?(x)?0,f(x)在区间(?1,0]单调递减,f(x)?f(0)?0;当
x?0,f?(x)?0,f(x)在区间(?1,0]单调递增,f(x)?f(0)?0;
综合之,得当x?0时,有f(x)?f(0)?0,原不等式成立. 六、 函数单调性、凹凸性判定、极值和最值:1. 确定函数y?x2(2?x)的单调区间、凹凸区间,极值和拐点。 解. 函数定义域(??,??)y??x(4?3x), 令y??0,得驻点x1?0,x3?y???4?6x,令y???0,得x2?列表 略432 3单减区间(??,0],[,??),单增区间?0,?,极大值y()?,极小值y(0)?033273??
凹区间(??,],凸区间[,??),拐点(,2.求y?(2x? 解. 函数定义域(??,??),
当x?0时,y??
略极小值y(1)??3,极大值y(0)?0.3. 从一块边长为a的正方形铁皮的四角截去同样大小的正方形,然后将四边折起做成一个无盖的盒子,问要截去多大的小方块,才能使盒子的容量最大。 解:设截去的正方形的边长为x,则盒子的容积为
V?(a?2x)?(a?2x)?x?x(a?22 x)令:V??(a?2x)2?x?2(a?2x)?(?2)?(a?2x)(a?6x)?0
得:x?4?4?4322323216). 32710,不可导点x1?0,驻点x2?1 3aa(舍),x?
264. 注:有关经济学的一些概念(印刷技术专业用): (1)成本C=固定成本+变动成本 (2)收入R=价格P×需求Q (3)需求Q=产量=销量 (4)利润L=收入R-成本C 七、 定积分的应用:1. 求由抛物线y?3?2x?x2与横轴所围成的面积。 解. 抛物线开口向下,与x轴交点(?3,0),(1,0)面积A?1313222(3?2x?x)dx?(3x?x?x)?. ??3?33312. 求曲线y?x2与y?x3所围图形的面积,分别绕x轴和y轴旋转的旋转体体积。 解:A?(x?x)dx?(x?x)??? ?003412341以下体积部分略:
Vx???11?2?46[(x)?(x)]dx??[x?x]dx??????0?0?5735??1223211?11??2334x[x?x]dx?2?[x?x]dx?2????
?0?0??45?101Vy?2?八、 证明题:(不要,略)1. 设F(x)?(x?1)2f(x),其中f(x)在?1,2?二阶可导,f(2)?0。试证存在??(1,2),使F??(?)?0。略2. 设f(x)在?a,b?上可导,且f(a)?f(b)?0,试证至少存在一点??(a,b),使得f?(?)?f(?)?0 (令F(x)?exf(x),用Roll定理) 九、 偏导数(印刷技术专业用)1. z?3xy?2?z?zx,求、?x?yy解:?z1?zx?6xy?,
?3x2?2 ?xy?yyz?x??u?u?u2. u???,求、、、duy?x?z?y??解:?uzx?z?xyz?1?x??x??u?x??x?zxz?1zxz?u?zx???ln??, du?zdx?z?1dy???ln??dz , ?z?1,?z?y??y?yy?yy?y??y?zzz

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