解方程:(1)9(x-2) 2 -121=0(2)x 2 -6x-2=0(配方法)(3)3(x-2) 2 =-2(2-x
1个回答

(1)移项:9(x-2) 2=121,

开方得:3(x-2)=±11,

解得:x 1=

17

3 ,x 2=-

5

3 .

(2)移项:x 2-6x=2,

∴x 2-6x+3 2=2+3 2

∴(x-3) 2=11,

∴x-3=±

11 ,

解得:x 1=3+

11 ,x 2=3-

11 .

(3)移项:3(x-2) 2-2(x-2)=0,

∴(x-2)[3(x-2)-2]=0,

即x-2=0,3(x-2)-2=0,

解得:x 1=2,x 2=

8

3 .

(4)整理得:2x 2+5x-7=0,

∴(2x+7)(x-1)=0,

即2x+7=0,x-1=0,

解得:x 1=-

7

2 ,x 2=1.