因式分解:(3x+5)^2(3x+7)(x+1)-4

问题描述:

因式分解:(3x+5)^2(3x+7)(x+1)-4

设3x+5=y原式=(1/3)(y^2)(y+2)(y-2)-4=(1/3)(y^2)(y^2-4)-4=(1/3)(y^4-4y^2-12)=(1/3)(y^2-6)(y^2+2)=(1/3)(y+√6)(y-√6)(y^2+2)=(1/3)(3x+5+√6)(3x+5-√6)(9x^2+30x+27)=(3x+5+√6)(3x+5-√6)(3x^2+10x+9)...