x(x-1)-(x的平方-y)=-2 ,求2分之x的平方+y的平方-xy的值

网友回答

x(x-1)-(x²-y)=-2
x²-x-x²+y=-2
-x+y=-2
x-y=2(x²+y²)/2-xy
=(x²-2xy+y²)/2
=(x-y)²/2
=2²/2
=2======以下答案可供参考======
供参考答案1:
x(x-1)-(x^2-y)=-2
x^2-x-x^2+y=-2
-x+y=-2
x-y=2(x^2+y^2)/2-xy
=(x^2-2xy+y^2)/2
=(x-y)^2/2
=4/2=2