Fourpvg
幼苗
共回答了21个问题采纳率:95.2% 举报
(x^2+3x+2)(4X^2+8x+3)-90
=(x+1)(x+2)(2x+3)(2x+1)-90 (十字相乘法)
=(x+1)(2X+3)(X+2)(2X+1)-90 (重新组合)
=(2x^2+5x+3)(2x^2+5x+2)-90 (组合后相乘)
设2x^2+5x=A
=(A+3)(A+2)-90=A^2+5A-84=(A+12)(A-7)=(2x^2+5x+12)(2x^2+5x-7)=(2x+7)(X-1)(2x^2+5x+12)
x^6-y^6=(X^3)^2-(y^3)^2
=(x^3+y^3)(x^3-y^3)
=(x+y)(x^2-xy+y^2)(x-y)(x^2+xy+y^2)
X^4-6x^2-7x-6
=x^4-4x^2-(2x^2+7x+6)
=x^2(x^2-4)-(2x+3)(x+2)
=(x+2)((x^2-2x)-(2x+3))
=(x+2)(x^2-4x-3)
1年前
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