x-y/x+y=(x-y)²/x²-y²(x≠y)

问题描述:

x-y/x+y=(x-y)²/x²-y²(x≠y)

这是正确的
(x+y)分之(x-y)
=(x+y)(x-y)分之(x-y)(x-y)
=(x²-y²)分之(x-y)²