z=f(x+y+z,xyz),求x对y偏导,

z=f(x+y+z,xyz),求x对y偏导, f为可微函数,z=f(x+y+z,xyz),z对x求导得多少,怎么求? 已知x+y-z/z=x-y+z/y=-x+y+z/x,且xyz不等于0,求分式[(x+y)(x+z)(y+z)]/xyz x+y+z=1 求xyz/(x+y)(y+z)(z+x)的最大值 z=f(x*x-y*y,e的XY次方)求Z对X偏导 Z对Y偏导 若xyz不等于0,且满足(y+z)/x=(x+z)/y=(x+y)/z,求（y+z)（x+z)（x+y)/xyz的值 若xyz不等于0,且(y+z)/x=(z+x)/y=(x+y)/z,求(y+z)(z+x)(x+y)/xyz的值? 若z分之x+y+z=y分之x-y+z=x分之-x+y+z,求xyz分之(x+y)(y+z)(z+x) (x+y-z)/z=(y+z-x)/x=(z+x-y)/y 求(x+y)(y+z)(z+x)/xyz 已知：(x+y-z)/z=(x-y+z)/y+(y+z-x)/x,且xyz≠0,求代数式[(x+y)(y+z)(x+z) 设Z=f(x+y+z,xyz),f具有二阶连续偏导数,求∂z/∂x. 若xy-z不等于0,且(y+x)/x=(z+x)/y=(y+x)/z,求[(y+z)(z+x)(x+y)]/xyz的值?