已知x-y=2.8y+z=9.2x+z=3x

已知x-y=2.8y+z=9.2x+z=3x (x+y-z)(x-y+z)= 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 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) 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/(y+z)+y/(z+x)+z/(x+y)=1 已知x,y,z满足x/(y+z)+y/(z+x)+z/(x+y)=1,求代数式x2/(y+z)+y2/(x+z)+z2/ 已知实数x,y,z满足x/(y+z)+y/(z+x)+z/(x+y)=1,求x2/(y+z)+y2/(z+x)+z2/( 已知3X=4X,5Y=6Z求X+Y：Y+Z 已知x=2,x+y+z=-2.8,求x^2(-y-z)-3.2x(z+y)的值 X+Y+Z=?