19.设f(x,y)?x?(y?1)arcsinx,则偏导数fx?(x,1)为 ( ) yA.2 B.1 C.-1 D.-2 解: f(x,1)?x?fx?(x,1)?1?B. 20. 设方程e?z = ( ) ?xzyzyA. B. C. D.
x(2z?1)x(2z?1)x(2z?1)x(2z?1)2z?xyz?0确定了函数z?f(x,y) ,则
解: 令F(x,y,z)?e2z?xyz?Fx???yz,Fz??2e2z?xy
?zyzyzz?2z???A. ?x2e?xy2xyz?xyx(2z?1)y221.设函数z?xy? ,则dzx?1? ( )
y?1xA. dx?2dy B. dx?2dy C.2dx?dy D. 2dx?dy
xdy?ydx2解:dz?2xydx?xdy? 2x?dzx?1?2dx?dy?dy?dx?dx?2dy?A.
?y?122.函数z?2xy?3x?3y?20 在定义域上内 ( ) A.有极大值,无极小值 B. 无极大值,有极小值 C.有极大值,有极小值 D. 无极大值,无极小值
22?z?z?2z?2y?6x?0,?2x?6y?0?(x,y)?(0,0)?2??6, 解:?x?y?x?2z?2z??6,?2? 是极大值?A. 2?x?y?y23设D为圆周由x?y?2x?2y?1?0围成的闭区域 ,则 A. ? B.2? C.4? D.16? 解:有二重积分的几何意义知:24.交换二次积分
A.C.
22??dxdy? ( )
D??dxdy?区域D的面积为?.
D?a0dx?f(x,y)dy(a?0,常数)的积分次序后可化为 ( )
0x??a0ady?f(x,y)dx B. ?dy?f(x,y)dx
0yaa0y0dy?f(x,y)dx D. ?dy?f(x,y)dx
00aaay解: 积分区域D?{(x,y)|0?x?a,0?y?x}?{(x,y)|0?y?a,y?x?a}
?B.
?25.若二重积分
??Df(x,y)dxdy??2d??02sin?0f(rcos?,rsin?)rdr,则积分区域D为
( )
22 A.x?y?2x B.x?y?2
C.x?y?2y D.0?x?22222y?y2
得分 解:在极坐标下积分区域可表示为:D?{(r,?)|0????2,0?r?2sin?},在直角坐标系下边界方程为
x2?y2?2y,积分区域为右半圆域?D
26.设L为直线x?y?1上从点A(1,0)到B(0,1)的直线段,则
( )
A. 2 B.1 C. -1 D. -2
0?x?xx解:L:?,从1变到0,?(x?y)dx?dy??dx?dx??2?D.
L1y?1?x??(x?y)dx?dy?
L27.下列级数中,绝对收敛的是 ( )
A.C.
?sinn?1?n?1??nn B.
?(?1)nsinn?1???n
?(?1)?n2?sin?n2 D.
??cosn?
n?1? 解: sin?n2???sinn?1nn?收敛?C. 2nn?028. 设幂级数
?an?0nx(an为常数n?0,1,2,?),在点x??2处收敛,则?(?1)an
( )
A. 绝对收敛 B. 条件收敛 C. 发散 D. 敛散性不确定 解:
?an?0?nx在x??2收敛,则在x??1绝对收敛,即级数?(?1)nan绝对收敛?A.
nn?0? 29. 微分方程sinxcosydy?cosxsinydx?0的通解为 ( ) A. sinxcosy?C B.cosxsiny?C C.sinxsiny?C D.cosxcosy?C 解:sinxcosydy?cosxsinydx?0?cosycosxdy??dx sinysinx?dsinydsinx???lnsiny?lnsinx?lnC?sinxsiny?C?C. sinysinx?x30.微分方程y???y??2y?xe的特解用特定系数法可设为 ( )
A. y??x(ax?b)eC.y??(ax?b)e?x?x B. y??x(ax?b)e?x2?x
?x D.y??axe
解:-1不是微分方程的特征根,x为一次多项式,可设y??(ax?b)e
二、填空题(每小题2分,共30分)
?C.
?1,|x|?1, 则f(sinx)?_________.
?0,|x|?1解:|sinx|?1?f(sinx)?1.
31.设函数f(x)??1?x?3?=_____________. 2x?2x?2x1?x?3(x?2)1?lim?lim? 解:lim2x?2x?2x?2x?2xx(x?2)(x?1?3)x(x?1?3)32.lim3.
4312 33.设函数y?arctan2x,则dy?__________.
??12dx. 21?4x3234.设函数f(x)?x?ax?bx在x??1处取得极小值-2,则常数a和b分别为___________.
2解:f?(x)?3x?2ax?b?3?2a?b?0,?2??1?a?b?a?4,b?5.
解:dy?35.曲线y?x?3x?2x?1的拐点为 __________.
2解:y??3x?6x?2?y???6x?6?0?(x,y)?(1,?1) .
3236.设函数f(x),g(x)均可微,且同为某函数的原函数,有f(1)?3,g(1)?1 则f(x)?g(x)?_________. 解:f(x)?g(x)?C?C?f(1)?g(1)?2?f(x)?g(x)?2. 37.
??(x??2?sin3x)dx?_________.
23?2?3?22?3解:?(x?sinx)dx??xdx??sinxdx?2?xdx?0?.
??????03x?2?e,x?038.设函数f(x)?? ,则 ?f(x?1)dx?__________.
20??x,x?0?2x . f(x?1)dx????f(t)dt?xdx?edx?e??0??1??1?03??a?{1,1,2}与向量b?{2,?1,1}的夹角为__________. 39.向量
??????a?b31?解:cos?a,b????????a,b?? .
3|a||b|662?y2?2x40.曲线L:绕x轴旋转一周所形成的旋转曲面方程为 _________. ??z?0222222解:把y?2x中的y换成z?y,即得所求曲面方程z?y?2x.
解:
2x?1?t1021?2z41.设函数z?xy?xsiny ,则 ?_________.
?x?y?2z?z?1?2xcosy. 解: ?y?2xsiny??x?y?x242.设区域D?{(x,y)|0?x?1,?1?y?1},则解:
??(y?xD2)dxdy?________.
1112222(y?x)dxdy?dx(y?x)dy??2xdx?? . ?????0?103D2 43.函数f(x)?e?x在x0?0 处展开的幂级数是________________.
??xn(?x2)n1?x2?f(x)?e????(?1)nx2n,x?(??,??) . 解: e??n!n!n?0n!n?0n?0x?xn?144.幂级数?(?1)的和函数为 _________. n?1(n?1)2n?0xx()n?1()nn?1???xxnn2n?12?(?1)?(?1)?ln(1?), 解:?(?1)??n?1n?1n2(n?1)2n?0n?0n?1(?2?x?2).
?x3x45.通解为y?C1e?C2e(C1、C2为任意常数)的二阶线性常系数齐次微分方程为_________.
?x3x2解:y?C1e?C2e??1??1,?2?3???2??3?0
?y???2y??3y?0 .
?n 得分 评卷人
46.计算 lim三、计算题(每小题5分,共40分)
1?x?e. 3x?0xsin2x2?x22?x2解:lim001?x?ex?0xsin32x?x2?lim1?x?ex?08x420?x20?lim?2x?2xex?032x3?x2?lime?1
x?016x2?x2211lime?x?? . 16x?016dy2sin2x47.求函数y?(x?3x)的导数.
dx2解:取对数得 :lny?sin2xln(x?3x),
12x?32sin2x 两边对x求导得:y??2cos2xln(x?3x)?2yx?3x2x?32sin2x所以y??(x?3x)[2cos2xln(x2?3x)?2sin2x]
x?3x?2(x2?3x)sin2xcos2xln(x2?3x)?(x2?3x)sin2x?1(2x?3)sin2x.
?lim?2xex?032x??48.求不定积分
?x24?x2x?2sintdx.
解:
?4sin2tdx?????2costdt?4?sin2tdt?2?(1?cos2t)dt
2cost??4?x2??t?22x2xxx4?x2?2t?sin2t?C?2arcsin?2sintcost?C?2arcsin??C.
2221ln(1?x)dx. 49.计算定积分??0(2?x)211ln(1?x)1ln(1?x)1 解:?dx?ln(1?x)d??dx ?0?0(2?x)202?x2?x0(2?x)(1?x)11111112?x21?ln2??(?)dx?ln2?ln?ln2?ln2?ln2.
302?x1?x31?x033?z?z,. 50.设z?f(2x?y)?g(x,xy) ,其中f(t),g(u,v)皆可微,求
?x?y?z?(2x?y)?g?u?g?v解: ?f?(2x?y)???x?x?u?x?v?x?(x,xy)?ygv?(x,xy) ?2f?(2x?y)?gu?z?(2x?y)?g?u?g?v?(x,xy). ?f?(2x?y)???f?(2x?y)?xgv?y?y?u?y?v?y51.计算二重积分I?2x??ydxdy, D1其中D由y?x,y?2x及x?1所围成.
解:积分区域如图06-1所示, 可表示为:0?x?1,x?y?2x.
所以 I?y 2 y?2x
??xD2ydxdy??dx?x2ydy
0x12xy?x
o 1 x 1y2314332??xdx()??xdx?x5?. 02x201001012x
52.求幂级数
?1?(?3)n?0?nn(x?1)n的收敛区间(不考虑区间端点的情况). ntn,这是不缺项的标准的幂级数. ?nn?01?(?3)?解: 令x?1?t,级数化为
1?1an?11?(?3)nn?11(?3)n因为 ??lim, ?lim??lim?n??an??1?(?3)n?1n??1n3n?3(?3)n?n1ntR??3,即级数收敛区间为(-3,3). 故级数?的收敛半径n?n?01?(?3)?nn(x?1)对级数?有?3?x?1?3,即?2?x?4. nn?01?(?3)故所求级数的收敛区间为. (?2,4)253.求微分方程 xdy?(2xy?x?1)dy?0通解.
21?x2解:微分方程xdy?(2xy?x?1)dx?0可化为 y??y?2,这是一阶线性微分方程,它对应的齐次线
xx2C性微分方程y??y?0通解为y?2.
xxC(x)xC?(x)?2C(x)?设非齐次线性微分方程的通解为y?,则,代入方程得 y?23xxx2C?(x)?1?x?C(x)?x??C.
211C故所求方程的通解为y???2.
x2x 得分 评卷人 四、应用题(每小题7分,共计14分)
2254. 某公司的甲、乙两厂生产同一种产品,月产量分别为x,y千件;甲厂月生产成本是C1?x?2x?5(千元),乙厂月生产成本是C2?y?2y?3(千元).若要求该产品每月总产量为8千件,并使总成本最小,求甲、乙两厂最优产量和相应最小成本.
解:由题意可知:总成本C?C1?C2?x?y?2x?2y?8,
约束条件为x?y?8.
问题转化为在x?y?8条件下求总成本C的最小值 .
把x?y?8代入目标函数得 C?2x?20x?88(x?0的整数).
则C??4x?20,令C??0得唯一驻点为x?5,此时有C???4?0. 故 x?5是唯一极值点且为极小值,即最小值点.此时有y?3,C?38. 所以 甲、乙两厂最优产量分别为5千件和3千件,最低成本为38千元.
55.由曲线y?(x?1)(x?2)和x轴所围成一平面图形,求此平面图形绕y轴旋转一周所成的旋转体的体积. 解:平面图形如图06-2所示,此立体可看作X型区域绕y轴旋转一周而得到。 利用体积公式Vy?2?222?bax|f(x)|dx.
显然,抛物线与x两交点分别为(1,0)、(2,0),平面图形在x轴的下方.