设球体X^2+Y^2+Z^2≤2*z各个点的密度等于该点到坐标原点的距离,求这球体的质量?怎么我积出来是0,

设球体X^2+Y^2+Z^2≤2*z各个点的密度等于该点到坐标原点的距离,求这球体的质量?怎么我积出来是0, 计算球体x^2+y^2+z^2 计算球体x^2+y^2+z^2 设球体X^2+Y^2+Z^2≤2*X上个点的密度等于该点到坐标原点的距离,求这球体的质量 设z=f(x^2-y^2,e^（xy)),求偏导z/x,偏导z/y 设函数z=z(x,y),由方程z=e^(2x-3z)+2y确定,求∂z/∂x,∂z/∂y 设函数z=z(x,y)由方程e^(-xy)-2z+e^z=0确定,求z/x,z/y 设x,y.z为实数,2x.3y.4z是等比数列,1/x,1/y.1/z是等差数列,则(x/z)+(z/x)是多少? 微积分...设z=z(x,y)是方程^2+y^2+z^2=y*e^z确定的隐函数,求dz.2x/(y*e^z-2z) dx + 2y/(y*e^z-2z) dy 设由方程x+2y+z=e^(x-y-z)确定的隐函数为z=z(x,y),求d^2z/dx^2 化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+（z-y)(x-y)/(x-2z+y)(y+z-2x)+(x-z)(y-z)/(y+z-2x)(x-2y+z) 计算:(y-x)(z-x)/(x-2y+z)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z)/(y+z-2x)(x-2y+z) 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 设X+Y+Z=0求X^3+X^2Z-XYZ+Y^2Z+Y^3的值 设x+y+z=11求函数u=2x*x+3y*y+z*z的最小值 设z=f(x^2,y,y/x)可导,求δz/δx,δz/δy 计算:x^2/(x-y)(x-z)+y^2/(y-x)(y-z)+z^2/(z-x)(z-y) 化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+（z-y)(x-y)/(xy-2z)(y+z-2x)+(x-z)(y-z)/(y+z-2x)(x-2y+z)速速回答