已知x>0,y>0,z>0,且xyz=1求证,x^3/（x+y）+y^3/（y+z）+z^3/（z+x）≥3/2

已知x,y,z都是正数,且xyz=1,求证：x^2/(y+z)+y^2/(x+z)+z^2/(x+y)≥3/2 已知方程组4x-y+3z=0 2x+y+6z=0且xyz不等于0,则x/y+y/z+z/x是多少 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 已知xyz满足|3x-2y+z|+|2x+y+2z|=0（xyz不等于o）求x+y除以z 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 代数式的恒等变形3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)(y 已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z都不为0,求（3x*x+y*y+4z*z）/（5x*x+y* 已知2X+5Y+4Z=0,3X+Y-7Z=0,且XYZ不等于0,求（X+Y+Z）/(2X-3Y+4Z)的值 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) 已知X,Y,Z为3个互不相等的实数,且X+1/Y=Y+1/Z=Z+1/Z求证(xyz)^2=1 已知2x-4y-5z=0,-3x+y+4z=0,（xyz≠0）则x：y:z=________ 已知一方程组：x-3y+7z=0与x-2y+4z=0(xyz≠0）,求x:y:z.