-4a的3次方b²+8a²b²=-4a²b²(a-2)9（a+b）²-4（a-b）²=(3a+3b+2a-2b)(3a+3b-2a+2b)=(5a+b)(a+5b)（x²+y²）²-4x²y²=(x²+y²+2xy)(x²+y
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