用实根法将多项式2x^3-x^2-5x-2分解因式
问题描述:
用实根法将多项式2x^3-x^2-5x-2分解因式
答
答:
2x^3-x^2-5x-2
=(2x^3-4x^2)+3x^2-5x-2
=2(x-2)x^2+(3x+1)(x-2)
=(x-2)(2x^2+3x+1)
=(x-2)(2x+1)(x+1)实根法实根法?试根法吧?x=2时:2x^3-x^2-5x-2=16-4-10-2=0x=1时:2x^3-x^2-5x-2=2-1-5-2=-6