-(x+1)二次方+9(x-2)二次方 - 知识问答

-(x+1)二次方+9(x-2)二次方

2个回答

答：
-(x+1)二次方+9(x-2)二次方
=-(x+1)²+9(x-2)²
=[3(x-2)]²-(x+1)²
=[(3(x-2)+(x+1)]*[3(x-2)-(x+1)]
=(4x-5)(2x-7)

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