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拜托了①(a-b)^4-(a+b)^2 ②2(x-y)(x+y)-(x+y)^2-(x-y)^2
人气:165 ℃ 时间:2020-06-21 01:16:11
解答
①(a-b)^4-(a+b)^2=[(a-b)²+a-b]*[(a-b)²-a-b]
②2(x-y)(x+y)-(x+y)^2-(x-y)^2 =-[(x+y)²-2(X+y)(x-y)+(x-y)²]=-[(x+y)-(x-y)]²=-4y²第一个好像错了
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