Question

分解(3a+b)^2-(3a-b)^2

Answer 1

原式=[(3a+b)-(3a-b)]*[(3a+b)+(3a-b)]
=2b*6a
=12ab

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追问

那-9/4x^2+25/16y^4如何分解

追答

原式=25y²/16-9x²/4
=(5y/4-3x/2)(5y/4+3x/2)
=(1/4)(5y-6x)(1/4)(5y+6x)
=(5y-6x)(5y+6x)/16

追问

25/16y^4不应该是（5/4y^2）^2么？

追答

好吧，看成平方了
原式=25y⁴/16-9x²/4
=(5y²/4-3x/2)(5y²/4+3x/2)
=(1/4)(5y²-6x)(1/4)(5y²+6x)
=(5y²-6x)(5y²+6x)/16