Question

一道一元二次方程， 3x^2+2x-1=0 怎么用配方法解啊？

本人基础差，请各位大侠一定要写详细点~拜托啦

Answer 1

3x^2+2x-1=0 解：3x^2+2x=1 x^2+2/3x=1/3 x^2+2/3x+(1/3)^2=1/3+1/9 (x+1/3)^2=28/9 x+1/3=±2√7/3 x=-1±2√7/3 x=2√7-1/3或x=-2√7-1/3

Answer 2

3x^2+2x-1=0
(3x-1)(x+1)=0
x=1/3 或 x=-1

Answer 3

3x^2+2x-1=0
x^2+2/3x-1/3=0
x^2+2*x*1/3+(1/3)^2-4/9=0
(x+1/3)^2-(2/3)^2=0
(x+1/3+2/3)(x+1/3-2/3)=0
(x+1)(x-1/3)=0
x+1=0,x-1/3=0
x1=-1,x2=1/3