用因式分解解方程(3x+1)(x-1)=(2x-5)(x-1)则整理为

问题描述:

用因式分解解方程(3x+1)(x-1)=(2x-5)(x-1)则整理为

(x-1)(3x+1+5-2x)=0
即: (x-1)(x+6)=0
则: x = 1 or x = -6
P.S. 答案 x = -2±√10 是错的,原因很简单,把答案带回等式即可验证

3x^2-2x-1=2x^2-7x+5

(3x+1)(x-1)=(2x-5)(x-1)
(3x+1)(x-1)-(2x-5)(x-1)=0
(x-1)(3x+1-2x+5)=0
(x-1)(x+6)=0
x=1,x=-6

(3x+1)(x-1)=(2x-5)(x-1)
3x^2-2x-1=2x^2-6x+5
x^2+4x-6=0
(x+2)^2=10
x+2=±√10
x=-2±√10