因式分解(x²+3x+2)(x²+7x+12)-120

(x^2+3x+2)(x^2+7x+12)-120=(x+1)(x+2)(x+3)(x+4)-120=(x+1)(x+4)(x+2)(x+3)-120=(x^2+5x+4)(x^2+5x+6)-120设y=x^2+5x+5 原式=(y-1)(y+1)-120=y^2-1-120=y^2-121=(y+11)(y-11)=(x^2+5x+16)(x^2+5x-6)=(x^2+5x+16)(x-1)(x+6)