已知x(x-1)-(x²-1)=-2,求(x²+y²)/2-xy

已知x(x-1)-(x²-1)=-2,求(x²+y²)/2-xy
已知x(x-1)-(x²-1)=-2,求(x²+y²)/2-xy

已知x(x-1)-(x²-1)=-2,求(x²+y²)/2-xy
x(x-1)-(x²-1)=-2
x²-x-x²+1=-2
-x+1=-2
x=2+1
x=3
(x²+y²)/2-xy
=(x²-2xy+y²)/2
=(x-y)²/2
没有y,解不出来!

第一个公式得出x-y=2 最后答案为2