2(x+y)(x-y)-(x+y)^2-(x-y)^2的完全平方公式是?

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2(x+y)(x-y)-(x+y)^2-(x-y)^2的完全平方公式是?

2(x+y)(x-y)-(x+y)^2-(x-y)^2的完全平方公式是?
2(x+y)(x-y)-(x+y)^2-(x-y)^2的完全平方公式是?

2(x+y)(x-y)-(x+y)^2-(x-y)^2的完全平方公式是?
=-[(x+y)²-2(x+y)(x-y)+(x-y)²]
=-[(x+y)-(x-y)]²
=(2y)²
=4y²

2(x+y)(x-y)-4xy
=2x²-4xy+2y²
=2(x-y)²
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