求函数z=x^2+y^2+4x-8y+2的极值

(x*x+2)(y*y+4)(z*z+8)=64xyz,求x,y,z 求函数z=x^2+y^2+4x-8y+2的极值 x+2y=3x+2z=4y+z 求x:y:z 设x+y+z=11求函数u=2x*x+3y*y+z*z的最小值 已知(z-x)∧2-4(x-y)(y-x)=0求x+z-2y+8的值写错了(z-x)∧2-4(x-y)(y-z)=0求x+z-2y+8 设函数z=z(x,y),由方程z=e^(2x-3z)+2y确定,求∂z/∂x,∂z/∂y 高数求梯度设函数f(x,y,z)=(x-y)2+(y-z)2+(z-x)2,求gradf(x,y,z).我算对了吗 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知x,y,z满足2x-y+4z=8,x-2y-z=7,求x-y+z的值.要2种方法 已知X、Y、Z满足2X-Y+4Z=8(1);X-2Y-Z=7(2)求X-Y-Z的值 已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值 已知:X、Y、Z满足2X-Y+4Z=8,X-2Y-Z=7,求X-Y+Z的值 求函数z=4(x-y)-x^2-y^2的极值 求二元函数z=y^3-x^2+4x-3y+1的极值 已知整数x、y、z,满足x≤y＜z,且｜x+y｜+｜y+z｜+｜z+x｜=4,｜x-y｜+｜y-z｜+｜z-x｜=2,求x^2+y^2+z^2的值. 整数x、y、z满足x≤y＜z|x+y|+|y+z|+|z+x|=4|x-y|+|y-z|+|z-x|=2求x²+y²+z²