x-y/x+y=(x-y)²/x²-y²(x≠y)

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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