例1(1)xx(1?lnx)dx?exlnx(1?lnx)dx?exlnxd(xlnx)?exlnx?C?xx?C
??? (2)
?ln(x?1?x2)ln(x?1?x2)dx??dx 221?x1?x ??ln(x?1?x2)dln(x?1?x2)
22 ?ln(x?1?x)3 (3)
??32?C
lntanxlntanx112dx?dx?lntanxdlntanx?(lntanx)?C ?sin2x?2sinxcosx?24sin2x2sinxcosxdcos2x2 (4)?dx??dx???arctan(cosx)?C 422221?cosx1?(cosx)1?(cosx) (5)
?x1?x2e1?x2dx??e1?x2d1?x?e21?x2?C
1?x4?x8例2、(1)(06年真题) ?dx
x(1?x8)1?x4?x8dx?解:(法一)?8x(1?x)1?x4x8?x(1?x8)dx??x(1?x8)dx
1x71?x4?x4x7dx??dx??dx??dx ??x(1?x4)1?x8x(1?x4)1?x81x3x7dx??dx ??dx??x1?x41?x8 ?lnx?11ln1?x4?ln1?x8?C 481x32x71?x4?x81?x8?x4?2x8dx??dx (法二) ?dx??dx??dx??x1?x81?x8x(1?x8)x(1?x8)x3x31x31x3 而 ?dx??dx??dx??dx 8444421?x21?x1?x(1?x)(1?x)1d(1?x4)1d(x4?1)11?x4??????ln||?C 44481?x81?x81?x
1?x4?x811?x41dx?ln|x|?ln||?ln|1?x8|?C 从而 ?84x(1?x)81?x4 ?lnx?11ln1?x4?ln1?x8?C 48e2xe2x?ex?exd(1?ex)xxxdx?dx?edx??e?ln(1?e)?C (2)?xxx???1?e1?e1?e(3)(07年的真题)求
?x9x?15dx
解:
?31x51x5?1?1525255dx??dx??dx?(x?1)2?x?1?C
55555155x?1x?1x?1x9ln2xdx?ln4x?x
ln2xdxln2xlnx?ln2??dlnx??ln4xx?ln4x?lnx?ln4dlnx
lnx?ln2?ln4?ln411 ??dlnx??dlnx?ln??d(lnx?ln4)
lnx?ln42lnx?ln4(4)(资料中的发挥题)求
?lnx?ln2?ln|ln4x|?C
11d(x?)2x?1xx例3、?4dx??dx???11x?1x2?2(x?)2?2xx111?d(x?)2x2?1?x4?1dx??2x1dx??12x?x?2(x?)?2xx21?221arctan(x?)?C 22x1?21xln?C
122x??2xx?x21?x2?1x2?1?dx???4dx??4dx? ?4x?12?x?1x?1?1?21111xarctan(x?)?ln?C ?1x42x??2222xx?11?x2?1x2?1?dx???4dx??4dx? ?4x?12?x?1x?1?1?21111xarctan(x?)?ln?C ?1x42x??2222xx?
(03年 真题)
???02??x?1?x21???x2?1dx?dx?dx??0? 444?01?x2?1?x1?x?1?2111??1xarctan(x?)0?ln ?x22242x?1?2xx?例4 (1)
??0?2? 411?sinx1?sinxdx?dx??1?sinx?(1?sinx)(1?sinx)?cos2xdx?tanx?secx?C
(类似地,求
111dx,dx,?1?cosx?1?cosx?1?sinxdx等)
x?1(x?1)exd(xex) (2)? dx??xdx??xx(1?xex)xe(1?xex)xe(1?xex)d(xex)d(xex)xex ????x?lnx?C xxexe?1xe?1 (4)
?1?x1?xdx??dx?arcsinx?1?x2?C 1?x1?x21stxf(t?)dx(s?0,t?0),则I之值( C ) ?0ss (A)依赖于s,t,x (B)依赖于s,t (C)只依赖于t (D)依赖于s,x
2tx1stx 解: 令u?t?,则x?su?st,I??f(t?)dx??f(u)du
tss0s1ln(1?x)例5(1)(资料中的发挥题)计算?dx
01?x2 *例5 若I???ln(1?x)ln(1?tant)dx??4dtant??4lntantdt 解:换元x?tant, 则 ?2201?x00sect1 再令t???4?u,有
?40?401?tanuln(1?tant)dt??ln(1?tan(?u))du??4ln(1?)du
041?tanu?????2du??4ln2du??4ln(1?tanu)du ??4ln0001?tanu?ln(1?x)?4dx?ln(1?tant)dt从而 ?=ln2 ?001?x281
(2)(07经管类真题)
???0dx(??0) 2?(1?x)(1?x)x?1t 解:I????0dx?2?(1?x)(1?x)???0??t?dtt??1?1??dt 2?2?0(1?t)(1?t)(1?t)(1?t) ????0??11???dt?dt?arctant|?I??I 022??01?t(1?t)(1?t)2 移项解得 I????0dx??
(1?x2)(1?x?)4?*(2)(05年数学类真题)计算
??20dx 20051?tanx解:令tanx?t 则
?20??dxdt? 200522005?0(1?t)(1?t)1?tanxx?1tI?? ???0dx?22005(1?x)(1?x)???0??t2005dtt2005?1?1??dt 22005220050(1?t)(1?t)(1?t)(1?t)???0??11???dt?dt?arctant|?I??I 0222005?01?t(1?t)(1?t)2 移项解得 I??4?,从而
?20??dxdt???
1?tan2005x?0(1?t2)(1?t2005)4(3)(首届高数竞赛真题) :证明:
?2?0sin(x2)dx?0
证明:
?2?0sin(x)dx?2?2t?x2?2?0?sint2?sintsintdt??dt??dt
0?2t2t2t 而
??sintt?u????sinudt??du
02t2u??从而 原式=
??0(sintsint?)dt?0 2t2t??例6(1)计算
??02sin9x?cos9xdx
1?7sinxcosx解:
??02??sin9x?cos9xsin9xcos9x22dx??dx??dx
01?7sinxcosx01?7sinxcosx1?7sinxcosx
而
???02cosxdx?1?7sinxcosx9t??x2???02sin9tdt
1?7costsint?0 从而
2??sin9x?cos9xsin9xcos9x22dx??dx??dx?0
01?7sinxcosx01?7sinxcosx1?7sinxcosx?0(2)(04 年真题)计算
???cosxdx 2x??x?2004t??x2解:
??0??cosxdx?x2??x?2004????sintdt ???2?2?(?t)??(?t)?20042?22??2????sintt2?2004??2?24dt??2???t2?2004??2?24?20dt??2??sintt2?2004?2?24dt
? ?2?202?tdt?0?arctan?2aa2t?2004?4??2?2004??2arctan?22004??2
44(3)(资料中的发挥题)计算
????0xsinxdx
1?cos2x(?t)cost?xsinx22dx?解:????21?sin2tdt 01?cos2xt??x2??dsinttcost222??dt?0 dt?dt ??????01?sin2t?1?sin2t?1?sin2t222??cost?? ??arctan(sint)20??24
xex1xexxexexxxx 例7(1)* ?dx???xed????edx???e??C 21?x1?x1?x1?x(1?x)1exexdx dx?a 求? (2)(资料中的发挥题)设?0(1?x)201?x11ex1exx?0(1?x)2dx???0ed1?x?1?x110exe??dx??1?a 01?x21