(x^2+3x+2)(4x^2+8x+3)-90
=（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)
x^9+x^6+x^3-3
=x^9-1+x^6+x^3-2
=(x^3-1)(x^6+x^3+1)+(x^3+2)(x^3-1)
=(x^3-1)[(x^6+x^3+1)+(x^3+2)]
=(x-1)(x^2+x+1)(x^6+2x^3+3)