第八章 不定积分
习题
§1 不定积分概念与基本积分公式
1. 验证下列等式,并与(3)、(4)两式相比照:
(1)?f/?x?dx?f?x??C; (2)?df?x??f?x??C
2. 求一曲线y?f?x?,使得在曲线上每一点?x,y?处的切线斜率为2x,且通过点?2,5?.
3. 验证y?x22sgnx是x在???,???上的一个原函数.
4. 据理说明为什么每一个含有第一类间断点的函数没有原函数? 5. 求下列不定积分:
(1)???1?2?1?x?x3???3?dx; (2)??x?1??x2????x?dx; ?(3)?dx; (4)?2x?3x2gx??2dx;
(5)?3 (6)?x24?4x2dx;3?1?x2?dx;
(7)?tan2xdx; (8)?sin2xdx;
(9)?cos2xcosx?sinxdx; (10)?cos2xcos2x?sin2;
xdx(11)?10t?32tdt; (12)?xxxdx;
(13)???1?x1?x???1??1?x?dx; (14)?cosx?sin?x??x?2dx;
(15)??cosx?cos2x?dx; (16)??ex?e?x?3dx
§2 换元积分法与分部积分法
1. 应用换元积分法求下列不定积分:
(1)?cos?3x?4?dx; (2)?xe2x2dx;
(3)?12x?1dx; (4)??1?x?ndx;
(5)???1?1?2x?3??3?x21?3x2?dx; (6)2dx;???
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(7)?8?3xdx; (8)?137?5xdx;
(9)?xsinx2dx; (10)?1??2?sin?2x??4??1dx;
(11)?1dx; (12)?dx;
1?cosx(13)?cscxdx; (15)?x 4?x4dx;(17)?x4?; 1?x5?3dx(19)?1x?1?x?dx; (21)?cos5xdx; (23)?1ex?e?xdx; x2(25)??2?x?1?3dx; (27)?1?x2?a2?3dx; 2(29)?x1?3xdx; 2. 应用分部积分法求下列不定积分:(1)?arcsinxdx; (3)?x2cosxdx; (5)??lnx?2dx; (7)??1??ln?lnx???lnx?dx?;
1?sinx(14)?xdx;
1?x2(16)?1xlnxdx;
(18)?x3x8?2dx;
(20)?cotxdx;
(22)?1sinxcosxdx; (24)?2x?3x2?3x?8dx;
(26)?1;
x2?a2dx(28)?x5
1?x2dx;(30)?x?1?1x?1?1dx.
(2)?lnxdx; (4)?lnxx3dx;
(6)?xarctandx; (8)??arcsinx?2dx; 2
(9)?sec3xdx; (10)?x2?a2dx?a?0?.
3. 求下列不定积分:
(1)??f?x???f/?x?dx????1?; (2)?f/?x?2;
1??f?x??dx/(3)?f?x?f?x?dx; (4)?ef?x?f/?x?dx.
4. 证明:
(1)若In??tannxdx,n?2,3,?,则I1n?1n?n?1tanx?In?2;
(2)若I?m,n???cosmxsinnxdx,则当m?n?0时,
m?1xsinn?1I?m,n??cosxm?1
m?n?m?nI?m?2,n?m?1
??cosxsinn?1x?n?1m?nm?nI?m,n?2?,n,m?2,3,?5. 利用上题的递推公式计算:
(1)?tan3xdx; (2)?tan4xdx;
(3)?cos2xsin4xdx.
6. 导出下列不定积分对于正整数n的递推公式:
(1)Inkxn??xedx; (2)In???lnx?ndx; (3)In???arcsinx?ndx; (4)I?xn??esinnxdx.
7. 利用上题的递推公式计算:
(1)?x3e2xdx; (2)??lnx?3dx;
(3)??arcsinx?3dx; (4)?exsin3xdx.
§3有理函数和可化为有理函数的不定积分 1. 求下列不定积分:
(1)?x3x?1dx; (2)?x?2x2?7x?12dx;
(3)?14)x3?1dx; (?1x4?1dx;
(5)?1?2?x?1??dx; (6)x2?1?2?x?2x2?2x?1?2dx.
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2. 求下列不定积分:
(1)?15?3cosxdx; (2)?12?sin2
xdx;2(3)?11?tanxdx; (4)?x;
1?x?x2dx(5)?1dx; (6)x?x2?11?xx21?xdx.
总练习题
求下列不定积分: (1)?x?23x?1x4dx; (2)?xarcsinxdx;
(3)?1x?1dx; (4)?esinxsin2xdx;
(5)?exdx; (6)?1;
xx2dx?1?tanx2 (7)?11?tanxdx; (8)?x?x?;
x?2?3dx (9)?110)4cos4xdx; (?sinxdx;
(11)?x?532 (12)x?3x?4dx;?arctan?1?x?dx;
(13)?x7414)?tanxx?2dx; (tanx?tan2x?1dx;
2 (15)?x(16)?arcsinx?1?x?100dx; x2dx;
(17)?xln??1?x??dx1?1?x (18) ? ?sinxcos7dx;x2 (19)?ex??1?x??1?x?dx;
? (20)In??vn,其中uudx?a1?b1x,v?a2?b2x,求递推形式解.
习题答案
§1 不定积分概念与基本积分公式
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2.y?x2?1.
.(1)x?x25x432?4?3x?C; (2)
x33?lnx?433x?C;
x (3)
2x(4)
4x9x?6g?C; ln4?ln9?2ln6?C;
(5)32arcsinx?C; (6)
13?x?arctanx??C;
(7)tanx?x?C; (8)
14?2x?sin2x??C;
(9)sinx?cosx?C; (10)?tanx?cotx?C;
t (11)
90ln90?C; (12)
815815x?C;
(13)2arcsinx?C; (14)x?12cos2x?C;
(15)
1?2?sinx?1sin3x???C; (16)1e3x?3ex?3e?x1?3x?3?3?3e?C;§2 换元积分法与分部积分法 1.(1)1sin?3x?4??C; (2)1e2x234?C;
(3)
1?x?n?12ln2x?1?C; (4)
?1n?1?C;
?2x?2 (5)arcsinx3?13arcsin3x??C;
(6)2ln2?C;
(7)?29?8?3x?3?C; (8)?33210?7?5x??C;
(9)?1cosx22?C; (10)?12cot??2x?????C; ?4? (11)tanx2?C; (12)tanx?secx?C;
(13)?lncscx?cotx?C; (14)?1?x2?C;
(15)1arctanx2 42?C; (16)lnlnx?C;
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