(1) 3x^3-2x-1 (2)x^3+6x^2+11x+6 (3)x^4+2x^3-9x^2-2x+8 (4) (x^2+3x+2)(x^2+7x+12)-120.因式分解
问题描述：
(1) 3x^3-2x-1 (2)x^3+6x^2+11x+6 (3)x^4+2x^3-9x^2-2x+8 (4) (x^2+3x+2)(x^2+7x+12)-120.因式分解
答
(1) 3x^3-2x-1=(3x+1)(x-1)(2)x^3+6x^2+11x+6=x^3+2x^2+4x^2+8x+3x+6=x^2(x+2)+4x(x+2)+3(x+2)=(x+2)(x^2+4x+3)=(x+2)(x+1)(x+3) (3)x^4+2x^3-9x^2-2x+8= x^4-2x^3+4x^3-8x^2-x^2+2x-4x+8=x^3(x-2)+4x^2(x-2)-x(x-2)...