分解因式:(x²+3x+2)(4x²+8x+3)-90
3个回答

﹙x²+3x+2)(4x²+8x+3)-90

原式=﹙x+2﹚﹙x+1﹚﹙2x+1﹚﹙2x+3﹚-90

=﹙x+2﹚﹙2x+1﹚﹙x+1﹚﹙2x+3﹚-90

=﹙2x²+5x+2﹚﹙2x²+5x+3﹚-90

设2x²+5x+2=t

=t﹙t+1﹚-90

=t²+t-90

=﹙t+10﹚﹙t-9﹚

=﹙2x²+5x+2+10﹚﹙2x²+5x+2-9﹚

=﹙2x²+5x+12﹚﹙2x²+5x-7﹚

=﹙2x²+5x+12﹚﹙2x+7﹚﹙2x-1﹚