已知x,y,z满足条件x+y-5z=0,x-y+z=0,求x?-y?/z?-x?的值,尽快!

Question

已知x,y,z满足条件x+y-5z=0,x-y+z=0,求x?-y?/z?-x?的值,尽快!

Answer 1

x+y-5z=0,x-y+z=0(x+y)(x-y)=5z*(-z)=-5z^2两式相加,x=2z则x^2=4z^2所以x?-y?/z?-x?=-5z^2/（-3z^2)=5/3