一元三次方程怎么解?如x3-3x+2=0求过程!
问题描述:
一元三次方程怎么解?
如x3-3x+2=0
求过程!
答
x^3-3x+2
=x^3-1+1-3x+2
=(x^3-1)-3(x-1)
=(x-1)(x^2+x+1)-3(x-1)
=(x-1)(x^2+x+1-3)
=(x-1)(x+2)(x-1)=0
所以x=1或-2