因式分 9(3m-5)²-25（m+1）² 快 - 知识问答

因式分 9(3m-5)²-25（m+1）² 快,在9点50之前发过来

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解
9(3m-5)²-25(m+1)²
=[3(3m-5)]²-[5(m+1)]²
=[3(3m-5)-5(m+1)][3(3m-5)+5(m+1)]
=(9m-5m-15-5)(9m+5m-15+5)
=(4m-20)(14m-10)
=8(m-5)(7m-5)

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