(x+2y+3z)(x-2y+3z) 有没有简便方法
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等.
x/2=y/3=z/5 x+3y-z/x-3y+z
1.(x+y-z)+(x-y+z)-(x-y-z) 2.2x-(3x-2y+3)-(5y-2)
已知|x-8y|+2(4y-1)²+3|8z-3x|=0,求x+y+z的值?简便方法用加减直接求出x+y+z
因式分解:25x y^2 z^2 (x+y-z)-30xyz(z-x-y)^2+5x y z^3 (z-x-y)
已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3
x=y/z=z/3,x+y+z =12,求2x+3y+4z是多少,
如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y,
(y-x)/(x+z-2y)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z
3道高数题,1,函数F(x,y,z)=(e^x) * y * (z^2) ,其中z=z(x,y)是由x+y+z+xyz=
{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2