求函数z=4(x-y)-x^2-y^2的极值

设x+y+z=11求函数u=2x*x+3y*y+z*z的最小值 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 求函数z=x^2+y^2+4x-8y+2的极值 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. 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 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 方程X/2=ln(z/y)确定的隐函数z=z(x,y) 求∂z/∂y,∂z/∂x. 求函数f(x,y,z)=x^2+y^2+z^2+2x+4y-6z的极值 求函数z=x^2y的全微分 求函数u=x^2+y^2+z^2+2x+4y+6z的极值 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 x+2y=3x+2z=4y+z 求x:y:z (x*x+2)(y*y+4)(z*z+8)=64xyz,求x,y,z 2|X-Y|+√2Y+Z+Z²-Z+1/4=0求X+Y+Z的值 设方程x+2y+z=e^(x-y-z),确定隐函数z=z(x,y),求对xy的二级偏导.