解下列一元二次方程: (1)(x-2)2=2x-4; (2)2x2-4x-1=0.

问题描述:

解下列一元二次方程:
(1)(x-2)2=2x-4;
(2)2x2-4x-1=0.

(1)∵x2-4x+4=2x-4
∴x2-6x+8=0
(x-2)(x-4)=0
解得:x1=2,x2=4;
(2)∵b2-4ac=

16+8
=2
6
>0,
.∴x=
4±2
6
4

x1
2+
6
2
  x2
2−
6
2