????(x)在[0,),(,?]上连续,在x?处,
222lim??(x)?lim?[1?c(x?x??2?2x??)]?1,lim??(x)?lim?sinx?1
x??22x??2故?(x)在x??2处连续
?cosx??(2)f(x)???x???2?解:令x?t?u,则当0?x?0?x?x?x?2,求
?2?tf(x?t)dt
0x0x?tf(x?t)dt?x?0x0xf(u)du??uf(u)du
0x?2时,
?x0x0f(u)du??cosudu?sinx
uf(u)du??ucosudu?xsinx?cosx?1
0 此时
x??tf(x?t)dt?1?cosx
0当x??2时,
?x0?f(u)du??20x2?x?2cosudu???(u?)du????1
22282x?323x?x?? ?uf(u)du??2ucosudu???(u?)udu?????1
002344822xx??x3?x2?2?3???(?1)x???1 此时?tf(x?t)dt?0648482x(九).补充换元计算
1、如果
I??f1(x)dxabbx?,令
b1I??f2(x)dxat得
则
2I??[f1(x)?f2(x)]dx?AaI? 得
A2
【例1】
I????01dxp2(1?x)(1?x)
x? 解:令
11dx??2dtt,即t
21
I????1dx??010(1?xp)(1?x2)???(?1(1?1t2)dt则
tp)(1?1t2)
?tp
???0(1?tp)(1?t2)dt
2I?1所以
???0(1?xp)(1?x2)???xpdx?0(1?xp)(1?x2)dx????dx01?x2??2I??4
?2dx2、形如
?1?tan?xy??0的积分,令2?x,然后相加处理
?【例2】?2cos2005x0cos2005x?sin2005xdx
t?? 解:令
2?x,则dx??dt
?cos2005x0cos2005(?t)I??22?0cos2005x?sin2005xdx????dt2cos2005(??t)?sin20052(?2?t)???2sin2005t0cos2005t?sin2005tdt
??2I?所以
?2cos2005x20050cos2005x?sin2005xdx??2sinx0cos2005x?sin2005xdx??2I??故4 Asinx?BcosxDcosxdx3、形如?Csinx?
令Asinx?Bcosx?a(Csinx?Dcosx)?b(Csinx?Dcosx)/确定a,b
3【例3】(1)?sinx?4cosxsinx?2cosxdx
解:令3sinx?4cosx?a(sinx?2cosx)?b(sinx?2cosx)/
??a?2b?3比较上式两端得?2a?b??4 即a??1,b??2
22
即
3sinx?4cosxsinx?2cosx(sinx?2cosx)/?sinx?2cosxdx???sinx?2cosxdx?2?sinx?2cosxdx??x?2ln|sinx?2cosx|?c sinxdx?(2)3sinx?4cosx
/sinx?a(3sinx?4cosx)?b(3sinx?4cosx)解:令
?3a?4b?134?a?b??4a?3b?0 即25,25 比较上式两端得?sinx33sinx?4cosx4(3sinx?4cosx)/?3sinx?4cosxdx?25?3sinx?4cosxdx?25?3sinx?4cosxdx34?x?ln|3sinx?4cosx|?c2525 1sec2xd[tanx]dx?dx?2?2?atan2x?b?atan2x?b处理
4、利用公式asinx?bcosx?【例4】
??20dx3sin2x?4cos2x
??dxsec2x1222?dx??03sin2x?4cos2x?04?3tan2x4?0解:
d[tanx]1?(3tanx2)2
?3tanx13tanx23?2?d[]?arctan()|?0?22122303tanx2231?()2
115、当f(x)在[?a,a]上可积,则
??【例5】(1)
?a?aa1af(x)dx??[f(x)?f(?x)]dx??[f(x)?f(?x)]dx02?a
1???41?sinxdx4?
?? 解:
11411144dx?[?]dx????41?sinx2???41?sinx1?sinx???41?sin2xdx??
dx??4??tanx|4??22?cosx?44
23
1??1(ex?1)(1?x2)dx(2)
111111dx?[???1(ex?1)(1?x2)2??1(ex?1)(1?x2)(e?x?1)(1?x2)]dx解:
11111?1??dx?arctanx|??1?11?x224 2bbI??f(x)dxI??f(b?x)dx00t?b?x6、积分,作变量替换得
b1bI?[?f(x)dx??f(b?x)dx]020则
【例6】
??0xsin2nxdx2n2nsinx?cosx
???0xsin2nx1?xsin2nx(??x)sin2n(??x)dx??[2n?]dx2n2n2n2n2n02sinx?cosxsinx?cosxsin(??x)?cos(??x)
???20?sin2nxsin2nxdx????dx2n2nsin2nx?cos2nxsinx?cosx2
2n令x??t2?sinx?2sin2nx?cos2nxdx?????20cos2nxdx2n2nsinx?cosx
???02n2n2xsin2nxsinxcosx?dx???2dx???2dx?2n2n2n2n2n2n002 sinx?cosx sinx?cosxsinx?cosx?
24
2005年浙江省普通高校“专升本”联考《高等数学(一)》试卷
二.选择题
2?e?x, x?01?3.设函数f(x)??0, x?0,则积分?f(x)dx=( ).
2?1??e?x, x?0?1(A)?1, (B)0 (C), (D)2.
e三.计算题 4.计算积分
--------------------------------------------密封线--------------------------------------------------------------------------------------------------- 11dx. 2??1x?3x?206.计算积分(x?x?2)edx.
0?2x
四.综合题
?1.计算积分sin0?2n?12m?1xsinxdx,其中n,m是整数. 22
2006年浙江省普通高校“专升本”联考《高等数学(一)》试卷
一、填空题:
(1?x3)cosx5.?? 。 dx?2 ? ___________________1?sinx2 2?二.选择题 3.设F(x)??x0?x2,0?x?1,则下面结论中正确的是( ) f(t)dt,其中f(x)???1,1?x?2 25