初中因式分解 （x2+3x+2)*(x2+7x+12)-120
问题描述：
初中因式分解 （x2+3x+2)*(x2+7x+12)-120
答
（X2+3X+2）（X2+7X+12）-120=[x^2+(2+1)x+1*2][x^2+(3+4)x+3*4]-120=(x+1)(x+2)(x+3)(x+4)-120=[(x+2)(x+3)][(x+1)(x+4)]-120=(x^2+5x+6)(x^2+5x+4)-120=(x^2+5x）^2+10(x^2+5x)+24-120=(x^2+5x)^2+10(x^2+5x)-96=(...那 (xy-1)2+(x+y-2)*(x+y-2xy)