? (4)?lim1?x2?113x-?0??x
0ln(1?t)dt1?x2?1 ?limx-?0?x
0ln(1?t)d(1?t)1?x2?1?0 ?limx?0??(ln??1)1(5)lim?x?0xx?x01(1?sin2t)tdt
?lim?01(1?sin2t)tx?0dt
1x洛必达法则lim(1?sinx)
x?0?lim(1?2x)x?01?2 2x?e2
lntdt1?t1(6)limx?1(x?1)2?x
lnx?lim1?xx?12x?2
11lnx1x?1?lim?limx?12x2?12x?12x41
1?(7)lim?x?????lim1x2?lim?x2x???ln(edt??e?0?t22x?x0edt)xt22
?ex???xt?ln?0edt?e1x2?x2?e
(8)limx????(arctant)dt
20x1?x2??x0x???x???(limarctan)2dtlim1?x2
?2?x???4lim1?x2?0
(9)?x???lim1x?x0(t?t2)et2?x2dt
?lim?x0(t?t2)etx?ex22x???dt
洛必达法则lim
(x?x2)ex22x???ex(1?2x)2?1 27.设F(x)在[a , b]上连续,且f(x)?0
F(x)??xaf(t)dt??xb1dt f(t)求证:(1)F ' (x)?2;
(2)F ' (x)在[a , b]内有且仅有一个实根.
解:证明: (1)设f(t)dt?g(t) ??1dt?h(t) f(t)F(x)?g(x)?g(a)?h(x)?h(b)?F ' (x)?g ' (x)-g ' (a)?h ' (x)-h ' (b)?f(t)?1f(t)
又因为f(t)?0 , ?F ' (x)?2
(2)因为F(x)在[a , b]上单调增加,又因为F(a)??ab1de??f(t)?ba1de?0 f(t)F(b)??baf(t)dt?0
又因为F(x)在区间[a , b]上连续. 所以在区间[a , b]内紧有一个实根. 8.设
f(x)为连续函数,且存在常数a满足
ex-1?x??axf(t)dt
求
f(x)及常数a.
解:设f(e)de?g(t)
?则ex?1?x?g(a)?g(x) 对等式两边求导,得:
ex?1?x?g ' (a)?g ' (x)??f(x)
所以所以
f(x)?1?ex?1
?axf(t)dt??axex?1dx?x?ex?1a?a?ea?1?ex?1?x x?1所以a?1 9.设 解:
Q ' (t)?f(t) , P ' (t)?Q(t)x?(x?t)f(t)dt?1?cosx,说明?0x?20f(x)dx?1.
?(x?t)f(t)dt0?tf(t)dt?x[Q(x)?Q(0)]?td(Q(t) ??x[Q(x)?Q(0)]?tdQ(t)?x?x[Q(x)?Q(0)]?tQ(t)?Q(t)dt0??x[Q(x)?Q(0)]?0x0x0x0x??Q(x)dt?1?cosx0x即
P(x)-P(0)?1-cosx?Q(x)?sinx?f(x)?cosx?
?2?f(x)dx?sinx02?10
10.用牛顿-莱布尼茨公式计算下列积分 (1)
?8dx (2)
1x?e?x)dx 13x?(e?12?12arcsinx2dx
21?x(5)
??0cosxdx (6)
?2xdx ?1?(9)
?ex2?lnx2d31xx (10)??tanxdx 62?4??x?1???d1?x?x ??(13)
?21?2?sindx (14)?1?sin2xdx 00?3max{1 , x2}dx
?1
解:(1)?8dx2x?32x381?9132
(2)?1(ex?e?x)dx?(ex?e?x)1?1?1?0 (3)
?e2(lnx)2e2(lnx)2d(lnx)?1e21xdx??(lnx)313122(4)
?12arcsinxdx?21?x2?12arcsinxdarcsinx
2?122arcsin2x21?2?21?2(16?36)
s3)
?e2(lnx)21xdx 7)
?1dx ?14?x2?11)??3tan2xdx 6?15)?xcosx?sinx?2dx4(xsinx)2(4)8)
?2dx04?x212)(16)
(((
((( ?5?2288
xx(5)
?x0cosxdx?2 cosxdx???cosxdx?sinx2?sinxx?2
x0022???(6)
?2?11xdx??20?1?xdx??20xdx?1221205x?x? 202?12(7)?(8)
dx4?x?1?arcsinx1??2?13
??2dx4?x20e?1x2?arctg? 2208(9)
1x2?lnx2dx?x?xdx??1ee121lnx1edx?x2?2x21?e1lnxdlnx
?e1121(e?1)?2(lnx)2?(e2?3)
1222??tanxdx??lncosx3(10)
??3??61ln3 26?(11)
???3tanxdx??3626?1cosx2??ldx??3(sec2x?1)dx
6??2ln2?1
?(3??3)?(3??) 36?442?3?36
1dx x(12)
?1(x?1x)2dx??1x?2x?1dx?x?411?2x?4?(x?44?lnx
1?2ln2?1
(13)
??20?111?sinxdx?6(?sinx)dx??2(sinx?)dx 2202???6