2024年1月10日发(作者:92年湖北中考数学试卷)

P.182 习题

1.验证下列等式

(1)f(x)dxf(x)C (2)df(x)f(x)C

f(x)dxf(x)C.

证明 (1)因为f(x)是f(x)的一个原函数,所以(2)因为duuC, 所以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).

解 由导数的几何意义, 知f(x)2x, 所以f(x)2f(x)dx2xdxx2C.

于是知曲线为yxC, 再由条件“曲线通过点(2,5)”知,当x2时,y5, 所以2有

52C, 解得C1, 从而所求曲线为yx1

2x2sgnx是|x|在(,)上的一个原函数. 3.验证y2x2x2证明 当x0时,

y,

yx; 当x0时,

y,

yx; 当x0时,

y22x(x2)sgnx0xsgnxlim0, 所以y0的导数为limx0x0x2x2x0x0|x|

x04.据理说明为什么每一个含有第一类间断点的函数都没有原函数?

解 由P.122推论3的证明过程可知:在区间I上的导函数f,它在I上的每一点,要么是连续点,要么是第二类间断点,也就是说导函数不可能出现第一类间断点。因此每一个含有第一类间断点的函数都没有原函数。

5.求下列不定积分

x2x433)dx1dxxdxxdxxdxx3x3C ⑴(1xx324x21231 152

1x342⑵(x)dx(x2x)dxxln|x|C

x33x122123⑶

dx2gxx12gxdx1212g2xC122xC

g⑷

(23x)2dx(22x2(23)x32x)dx(4x26x9x)dx

4x26x9xC

ln4ln6ln9⑸

344x2dx313dxarcsinxC

221x2x2x211111⑹

dxdx(1)dx(1arctanx)C

3(1x2)333(1x2)1x2⑺

22tanxdx(secx1)dxtanxxC

2sinxdx1cos2x111dx(1cos2x)dx(xsin2x)C

2222cos2xcos2xsin2xdxdx(cosxsinx)dxsinxcosxC ⑼

cosxsinxcosxsinx⑽cos2xcos2xsin2x11dxdx(cos2xsin2xcos2xsin2xsin2xcos2x)dxcotxtanxC

(109)t90tCC ⑾

103dt(109)dtln(109)ln90t2tt⑿

8xxxdxxdxx8C

157815⒀

(1x1x1x1x2)dx()dxdx2arcsinxC

2221x1x1x1x1x 153

2(cosxsinx)dx(1sin2x)dx1dxsin2xdxx12cos2xC

111(cos3xcosx)dx(sin3xsinx)C

22313x13xxx33xxx3xxx⒃

(ee)dx(e3e3ee)dxe3e3eeC

33⒂

cosxcos2xdxP.188 习题

1.应用换元积分法求下列不定积分:

11cos(3x4)d(3x4)sin(3x4)C

3312x212x22x22⑵

xedxed(2x)eC

44dx1d(2x1)1⑶

ln|2x1|C

2x122x121nn⑷

(1x)dx(1x)d(1x)(1x)n1C

n1⑴

cos(3x4)dx⑸(

13x2113x2)dx123x13xx1arcsinarcsin3xC33dx1312)d3x

22x312x322x322x2dx2d(2x3)CC

22ln2ln2133⑺

11222283xdx(83x)d(83x)(83x)C(83x)2C

33391133333(75x)d(75x)(75x)C(75x)C

5521075x2xsinxdx⑻

dx1223⑼

11222sinxdxcosxC

22)141cot(2x)C ⑽

224sin2(2x)sin2(2x)44dxd(2x 154

⑾ 解法一:

xxcos222dx(1cosx)dxdxcosxdx解法二:

2221cosx1cosxsinxsinxdsinx1cotxcotxC

2sinxsinx2cos2⑿解法一:利用上一题的结果,有

dx1cosxdxdx2tanxC

2d(2x)dx1xtan(x)Ctan()C

1sinx22421cos(x)2dx(1sinx)dxdxdcosx1解法二:

tanxC

2221sinxcosx1sinxcosxcosx解法三:dxdxdx1sinx(sinx2cosx2)2cos2x2(tanx21)2

2dtanx22C

(tanx21)2tanx21⒀ 解法一:cscxdxsec(2x)dxsec(2x)d(2x)

ln|sec(2x)tan(2x)|Cln|cscxcotx|C

解法二:cscxdx1sinxdcosx1cosx1dxdxsinxsin2xcos2x12lncosx1C

ln|cscxcotx|C

cscx(cscxcotx)cscxcotxdx

d(cscxcotx)Cln|cscxcotx|C

cscxcotxx解法四:sin12cscxdxdxdx

xxxx2sincos2sin2cos2222解法三:cscxdx 155

x1x2xxxdcotln|cot|Cln|tan|C

x222cot211d(1x2)1x2C

21x21⒁

dxx111x22⒂

dxdxarctanC

24(x2)2424x4⒃

dxdlnxxlnxlnxln|lnx|C

x411115⒄

dxd(1x)C

5353525(1x)10(1x)(1x)x3114dxdx⒅

84(x4)22x211x21x2ln|4|Cln|4|C422x282x244

dx11x()dxln|x|ln|1x|Cln||C

x(1x)x1x1x⒇

cotxdxcosxdxln|sinx|C

sinx(21)

5422cosxdxcosxcosxdx(1sinx)dsinx

21(12sin2xsin4x)dsinxsinxsin3xsin5xC

35dxd(2x)(22) 解法一:ln|csc2xcot2x|C

sinxcosxsin2xdxcosxdxdtanx解法二:ln|tanx|C

2sinxcosxtanxsinxcosxdx(sin2xcos2x)dx解法三:

sinxcosxsinxcosx(sinxcosx)dxln|sinx|ln|cosx|C

cosxsinx 156

dxexdxdexxarctaneC (23)

xx2x2xeee1e12x3d(x23x8)dx2ln|x23x8|C (24)

2x3x8x3x8x22(x1)22(x1)3dxdx(25)

33(x1)(x1)

12323()dxln|x1|C232x1(x1)x12(x1)(x1)(26)

dxdxxa22

解 令xatant, 则

asec2tdtln|secttant|C1ln|xx2a2|C

asectx2a2dx1x1xd(x2a2)32a2(x2a2)12a2(x2a2)12C (27)

解法2 令xatant, 则

dxasec2tdt11xcostdtsintCC

2(x2a2)32a3sec3ta2222aaxa(28)

x5x51x2dx

解 令xsint, 则

sin5tcostdxdtsin5tdt(1cos2t)2dcostcost1x2123252

2121costcos3tcos5tC(1x2)(1x2)(1x2)C3535(29)

116x3xdx

65解 令xt, 则xt,

dx6t

157

t3t5dt(t2)411(t21)(t6t4t21)1dt213xdx61t261t2dt61t

7531ttt6t16((t6t4t21))dt6(t)ln||C7532t11t2x其中tx

(30)

16x11x11dx

2解 令x1t, 则x1t,

dx2tdt,

x11x11dxt124t42tdt(1)2tdt(2t)dt(2t4)dtt1t1t1t1

t24t4ln|t1|C1x14x14ln|x11|C1x4x14ln|x11|C2.应用分部积分法求下列不定积分:

arcsinxdxxarcsinxx1x2dxxarcsinx1x2C

1lnxdxxlnxxxdxxlnxxC

222xcosxdxxdsinxxsinx2xsinxdx⑶

x2sinx2xdcosxx2sinx2xcosx2cosxdx

x2sinx2xcosx2sinxC⑷

lnx111lnx11lnx1dxlnxddxC

x322x22x3x22x24x2222(lnx)dxx(lnx)2lnxdxx(lnx)2xlnx2xC

1121x22dx ⑹

xarctanxdxarctanxdxxarctanx22221x1211121xarctanx(1)dxxarctanx(xarctanx)C

22221x211(x21)arctanxxC

22158

[ln(lnx)11]dxln(lnx)dxlnxdx

lnx11xln(lnx)xdxdxxln(lnx)C

xlnxlnx22(arcsinx)dxx(arcsinx)⑻

2xarcsinx1x2dx

x(arcsinx)22arcsinxd1x2

x(arcsinx)221x2arcsinx21x211x2dx

x(arcsinx)221x2arcsinx2xC

sec3xdxsecxdtanxsecxtanxsecxtan2xdx

secxtanxsecx(sec2x1)dxsecxtanxsec3xdxsecxdx

secxtanxsec3xdxln|secxtanx|

所以

3secxdx1secxtanxln|secxtanx|)C

2xxa22⑽

x2a2dxxx2a2x2222dx

xxa(xa2222a2xa22)dx

xxaxadxa2xa22dx

xx2a2x2a2dxa2ln(xx2a2)

所以

x2a2dx1(xx2a2a2ln(xx2a2))C

2类似地可得

x2a2dx1(xx2a2a2ln(xx2a2))C

2159

3.求下列不定积分:

[f(x)]f(x)dx[f(x)]df(x)⑵

aa1[f(x)]a1C

a1f(x)1dx1[f(x)]21[f(x)]2df(x)arctanf(x)C

f(x)df(x)dxln|f(x)|C

f(x)f(x)⑷

ef(x)f(x)dxef(x)df(x)ef(x)C

4.证明:

⑴ 若Intannxdx,n2,3,,则In1tann1xIn2

n1证

Intann2x(sec2x1)dxtann2xsec2xdxtann2xdx

tann2xdtanxIn2.

因为tann2xdtanxtann1x(n2)tann2xdtanx,

所以tan从而Inn2xdtanx1tann1x.

n11tann1xIn2.

n1⑵ 若I(m,n)cosmxsinnxdx,则当mn0时,

cosm1xsinn1xm1I(m,n)I(m2,n)

mnmncosm1xsinn1xn1I(m,n2),n,m2,3,

mnmn证

I(m,n)cosxsinxdxmn1m1n1cosxdsinx

n11[cosm1xsinn1x(m1)cosm2xsinn2xdx]

n11[cosm1xsinn1x(m1)cosm2xsinnx(1cos2x)dx]

n11[cosm1xsinn1x(m1)(I(m2,n)I(m,n))]

n1160

cosm1xsinn1xm1I(m2,n), 所以I(m,n)mnmncosm1xsinn1xn1I(m,n2) 同理可得I(m,n)mnmn

P.199 习题

1.求下列不定积分:

x3x3111dxdx(x2x1)dx ⑴

x1x1x1x3x2xln|x1|C

32x221(x4)2dx()dxlnC ⑵ 解法一:2x4x3|x3|x7x12解法二:

x212x713dxdxdx

22x27x122x7x122x7x121d(x27x12)3222x7x1217d(x)

712(x)22413x4ln|x27x12|lnC

22x311ABxC

3221x1x(1x)(1xx)1xx2⑶ 解

去分母得

1A(1xx)(BxC)(1x)

令x1,得A13. 再令x0,得AC1,于是C23. 比较上式两端二次幂的系数得

AB0,从而B13,因此

dx1dx1x21x331x31xx2dx 161

112x111ln|1x|dxdx361xx221xx21111ln|1x|ln(1xx2)dx362(x12)2341(1x)212x1lnarctanC

61xx233dx1(1x2)(x21)11x21x21dxdxdx ⑷ 解

44442221x1x1x1x11111d(x)d(x)221111xxxxdxdx

1122122122x2x2x22x22xxxx11d(x)d(x)1x1x

12122(x)2(x)22xx1122xarctan11x2x1lnxC

1242x2x2x212x22x1arctanln2C

482xx2x1⑸dx(x1)(x21)2

1ABxCDxE, 解得

(x1)(x21)2x1x21(x21)2解 令A111,

BC,

DE, 于是

442dx1dx1x11x1dx(x1)(x21)24x14x212(x21)2dx

162

111111xln|x1|ln(x21)arctanx(arctanx)C

24844x214x11|x1|1x(ln2arctanx2)C

24x1x1x214x251dxdxdx

2222(2x22x1)24(2x2x1)2(2x2x1)⑹

4x2d(2x22x1)1其中

dx22222(2x2x1)(2x2x1)2x2x1141dxdx2(2x22x1)2[(2x1)21]2[(2x1)21]2d(2x1)

2x1arctan(2x1) 参见教材P.186 例9或P.193关于Ik的递推公式⑺.

2(2x1)1于是,有

x21152x15dxarctan(2x1)C

22(2x22x1)242x2x12(2x1)125x35arctan(2x1)C

22(2x2x1)22.求下列不定积分

dx53cosx

x解 令ttan,则

2⑴

dx53cosxdx2dtdt1d(2t)1arctan2tC

222221(2t)21t1t14t531t21xarctan(2tan)C

22dxdxdxdtanx2sin2x2cos2x3sin2x(23tan2x)cos2x(23tan2x) ⑵

163

3tanx)1132arctan(tanx)C

326(1tan2x)62d(dxcosxdx1cosxsinxsinxcosxdx

1tanxcosxsinx2cosxsinx1sinxcosx1d(sinxcosx)(1)dx(dx)

2cosxsinx2cosxsinx1(xln|cosxsinx|)C

2cosxdxsinxdx另解:设I1,I2,

cosxsinxcosxsinxcosxsinx则I1I2dxxC,

cosxsinxcosxsinxd(cosxsinx)I1I2dxln|cosxsinx|C

cosxsinxcosxsinxdx1所以I1(xln|cosxsinx|)C

1tanx2⑶

x21xx2dx1xx2dx(x1)dx1xx2

1xx2dx1(2x1)dx3dx

21xx221xx2其中(利用教材P.185例7的结果)

1xx2dx(2x1)dx1xx2dx1xx251152x11(x)2dx[arcsin(x)1xx2]

42242521xx2

2x15d(1xx2)1xx2dx51(x)242arcsin

所以有

164

x21xx2dx

152x11132x1[arcsin(x)1xx2]21xx2arcsinC

242225572x12x3arcsin1xx2C

845⑸

dxxx21d(x)12ln|xx2x|C

211(x)224⑹

1x21xdx

1x1x1t24tdtdx解 令

t,则x,,代入原式得

2221x(1t)1t1x2421t21xdx1t21x4t4t21t21t(1t2)2dt(1t2)2dt4(1t2)2dt

2111112dt4dt4dt[(1t2)21t2(1t)2(1t)21t2]dt

1t21111t11dt[]dtln||C

2221t1t1t1t(1t)(1t)11x21x2ln||C

xx总 练 习 题

求下列不定积分:

x23x14xdx(x2x4241244x)dxx4xxC

5133 165

xarcsinxdxx2112122arcsinxdx[xarcsinxx1x2dx]

22其中sin2t1cos2t11dxcostdtdt(tsin2t)

cost2221x21(arcsinxx1x2)

2121[xarcsinxx2dx]

221x所以xarcsinxdx11[x2arcsinx(arcsinxx1x2)]C

22111x2arcsinxarcsinxx1x2C

244⑶

1dxx

解 令xu,则dx2udu

1dxx2udu12(1)du2(uln|1u|)C

1u1u2(xln|1x|)C

sinxsinxsinxsinx

esin2xdx2esinxcosxdx2esinxdsinx2sinxde2(esinxsinxesinxdsinx)2(esinxsinxesinx)C2esinx(sinx1)C

exxdx(令xu)eu2udu2(euueu)C2ex(x1)C

dxx21dxx211x211d()arcsinC

xx112x1⑹

解法二:令xsect,

x

dxx21secttant1dttCarccosC

secttantx166

1tanxcosxsinxd(cosxsinx)dxdx1tanxcosxsinxcosxsinx

ln|cosxsinx|C

1tanxdxtan(x)dxln|cos(x)|C

1tanx44x2x(x2)23(x2)231⑻

dxdxln|x2|C

x2(x2)2(x2)3(x2)3dxdx122secx(1tanx)dtanxtanxtan3xC

2cos4x3cosx1cos2x2422⑽

sinxdx(sinx)dx()dx

2111cos4x(12cos2xcos22x)dx(12cos2x)dx

4421xsin4x311(xsin2x)Cxsin2xsin4xC

4288432x5⑾

3dx

2x3x4⑼解

x5x5dxx33x24(x1)(x2)2dx

令x5ABC

(x1)(x2)2x1x2(x2)22去分母得:x5A(x2)B(x1)(x2)C(x1)

解得:A所以22,B,C1

33x521211dxdxdxx33x24(x2)2dx

3x13x22x21ln||C

3x1x2⑿

arctan(1x)dx

解 令1xu,dx2(u1)du

167

arctan(1x)dxarctanu2(u1)du2arctanuudu2arctanudu

[(u21)arctanuu]2uarctanuln(1u2)C1

xarctan(1x)xln(2x2x)C

x7x72x32x32x33dxdx(x4)dx ⒀

44x2x2x2141xln(x42)C

42x7x4x31211dx4dx(14)dx4x4ln(x42)C 另解:4442x2x2x2tanx1tanxtan2xdx

解 令tanxu

tanxu111dxdudu1tanxtan2x1uu21u21u21uu2du

arctanu23arctan2u13Cx23arctan2tanx13C

x2(1x)22(1x)1⒂

dxdx

100100(1x)(1x)111C

99989799(1x)49(1x)97(1x)⒃

arcsinx1arcsinx1dxarcsinxdx2x1x2dx

xxarcsinx11x2ln||C

xx⒄

xln1x1dxx[ln(1x)ln(1x)]dx[ln(1x)ln(1x)]dx2

1x2121211x211xx[ln(1x)ln(1x)]x()dxlnxC

221x1x21x 168

1sinxcosx7dx1tanxcosx4dx1tan2xtanxdtanx

12tanx(1tan2x)C

521x2ex2xx1x2xx⒆

e()dxedxdxedx

2222221x(1x)1x(1x)xex1exexexexxdxeddxdxC

2222221x1x1x1x1x1x⒇

Invnudx,ua1b1x,va2b2x

Invnudx2n2nvdu[vunub2vn1dx]

b1b1b2uvn1(b1va1b2a2b1)vn12n2n[vundx][vundx]

b1b1uu2n[vunb1Inn(a1b2a2b1)In1]

b12[vnun(a1b2a2b1)In1]

(2n1)b1所以In

169


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