x^2-4x+m-1=0 怎么求根

问题描述:

x^2-4x+m-1=0 怎么求根

x^2 -4x + m-1= 0
x^2 -4x +4 + m -5 = 0
(x-2)^2 = 5-m
1)5-m 2)5-m=0:x=2
3)5-m>0
x-2 = +- (5-m)^1/2
x1 = - (5-m)^1/2 +2
x2= (5-m)^1/2 +2