已知x=-2,x+y+z=-2.8,求x2(-y-z)-3.2x(z+y)的值.
已知x=-2,x+y+z=-2.8,求x2(-y-z)-3.2x(z+y)的值.
已知x=2,x+y+z=-2.8,求x^2(-y-z)-3.2x(z+y)的值
已知|x+(-2)|+|y+3|+|z|=0,求x+y+z的值.
已知x::y:z=3:4:5,(1)求x+y分之z的值;(2)若x+y+z=6,求x,y,z.
已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/(除以)x-y+z的值.
已知x、y、z满足方程组:x+y-z=6;y+z-x=2;z+x-y=0 求x、y、z的值
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x,y,z满足方程组{x+y-z=6{y+z-x=2{z+x_y=0,求x,y,z的值
已知x-y=2,y-z=2,x+z=14,求x2-z2的值.
已知x=3y,z=7y(x≠0),求代数式2x+3y-z分之x+y+z的值
x y z x+y--- = --- = ---- ----y+Z z+x x+y ,求 z 的值 .求 x+y----