已知x(x-1)-(x^2-y)=-3,求x^2+y^2-2xy的值

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

已知x(x-1)-(x^2-y)=-3,求x^2+y^2-2xy的值
x(x-1)-(x^2-y)=-3
x^2-x-x^2+y=-3
-x+y=-3
x-y=3
所以x^2+y^2-2xy
=(x-y)^2
=3^2
=9

居然在这里遇到至天使-