已知x(x-1)-(x^2-y)=-3,求3x^2+3y^2-6xy的值

已知x(x-1)-(x^2-y)=-3,求3x^2+3y^2-6xy的值
已知x(x-1)-(x^2-y)=-3,求3x^2+3y^2-6xy的值

已知x(x-1)-(x^2-y)=-3,求3x^2+3y^2-6xy的值
x(x-1)-(x^2-y)=-3
x^2-x-x^2+y=-3
-x+y=-3
x-y=3
原式=3(x^2-2xy+y^2)
=3(x-y)^2
=3×3^2
=27

前式推得y－x＝－3
后式子＝3（y－x）²＝27

x(x-1)-(x^2-y)=-3===》-x+y=-3,y=x-3
3x^2+3y^2-6xy =3(x-y)^2=3*3^2=27

前式推得y－x＝－3；x-y=3;
后式子＝3（x^2－2xy+y^2)＝3(x-y)^2=27

由已知可得 x^2-x-x^2+y=-3
-x+y=-3
x-y=3
原式==3(x-y)^2=27