求因式分解:(x^2+3x+2)(4x^2+8x+3)-90

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求因式分解:(x^2+3x+2)(4x^2+8x+3)-90

求因式分解:(x^2+3x+2)(4x^2+8x+3)-90
求因式分解:(x^2+3x+2)(4x^2+8x+3)-90

求因式分解:(x^2+3x+2)(4x^2+8x+3)-90
原式=(x+1)(x+2)(2x+3)(2x+1)-90
=[(x+1)(2x+3)][(x+2)(2x+1)]-90
=(2x^2+5x+3)(2x^2+5x+2)-90
=(2x^2+5x)^2+5(2x^2+5x)-84
=(2x^2+5x-7)(2x^2+5x+12)
=(x-1)(2x-7)(2x^2+5x+12)

-84 + 25 x + 35 x^2 + 20 x^3 + 4 x^4 = (-1 + x) (7 + 2 x) (12 + 5 x + 2 x^2)