16 单选 (4分)设 =f(x,xy,xyz), f可微,则偏导数计算正确的是 () .-|||-A. dfrac (partial u)(partial y)=x(f)_(2)+x=(f)_(3)-|||-① B. dfrac (partial u)(partial x)=(f)_(1)+(f)_(2)+(f)_(3)-|||-C. dfrac (partial u)(partial u)=xve-|||-bigcirc D. dfrac (partial u)(partial x)=(1+y+yz)f'

求内接于椭球(x^2)/(a^2)+(y^2)/(b^2)+(z^2)/(c^2)=1的最大长方体的体积V.下列解法过程中错误的是（）.A. V=(8abc)/(3sqrt(3))B. 设(x,y,z)是各面平行于坐标面的内接长方体在第一卦限内的顶点，则问题归结于求: (x^2)/(a^2)+(y^2)/(b^2)+(z^2)/(c^2)=1下，V=2x2y2z=8xyz的最大值.C. 问题可转化为拉格朗日函数为L(x,y,z,lambda)=xyz+lambda((x^2)/(a^2)+(y^2)/(b^2)+(z^2)/(c^2)-1)的极值问题D. V=(abc)/(3sqrt(3))

函数z=2-sqrt(x^2+y^2)在点(0,0)处有()A. 没有最值B. 极小值C. 极大值D. 没有极值

设=f(dfrac (x)(y),dfrac (y)(z)), f可微,则偏导数计算错误的是 () .-|||-(4分)-|||-A dfrac (partial u)(partial z)=-dfrac (y{f)_(2)'}({z)^2}-|||-B 其他选项中有正确的选项-|||-C dfrac (partial u)(partial x)=dfrac (f'')(y)-|||-D dfrac (partial u)(partial y)=-dfrac (x{f)_(1)}({y)^2}+dfrac (y{f)_(2)'}(z)

微分方程y'-y=0的通解为( ).A. y=e^x+CB. y=e^-x+CC. y=Ce^xD. y=Ce^-x

3、单选 lim _(x arrow 0) (xy)/(x^2)+y^(2)=( )A. 1B. 0C. 1/2D. 不存在

关于极限lim _((x,y)arrow (0,0))dfrac (x{y)^2}({(x-y))^2}描述正确的是（）A 不存在B 值 1 C 值 0 D其他选项都不对

(填空题)已知 approx N(1.5,4), 则(|X|gt 3)=-|||-(注: (0.75)=0.773 circled (4)(2.25)=0.988 若结果-|||-不为整数,请用小数表示,且小数点后保留3位-|||-数字)3) = &(注:phi (0.75) =0.773, phi (2.25) =0.988若结果&不为整数,请用小数表示,且小数点后保留3位&数字) end (aligned)" data-width="387" data-height="125" data-size="18103" data-format="png" style="max-width:100%">

函数z=e^2x (x + y^2 + 2y )在()处取得极()值，该极值为().A. ((1)/(2), -1 )，小，-(e)/(2)B. (0, (1)/(2) )，大，(e)/(2)C. ((1)/(2), -1 )，大，0D. (0, (1)/(2) )，小，-(e)/(4)

热门问题