总共三道

题目

总共三道
3（x+2）^2=x^2-4
3（x-2）^2=2x^2-4x
9(x+1)^2=4(1-2x)^2

答案

3（x+2）^2=x^2-4
3(x+2)^2-(x+2)(x-2)=0
(x+2)[3(x+2)-(x-2)]=0
(x+2)(2x+8)=0
x=-2,x=-4
3（x-2）^2=2x^2-4x
3(x-2)^2-2x(x-2)=0
[3(x-2)-2x](x-2)=0
(x-6)(x-2)=0
x=6,x=2
9(x+1)^2=4(1-2x)^2
[3(x+1)]^2-[2(1-2x)]^2=0
(3x+3)^2-(2-4x)^2=0
(3x+3+2-4x)(3x+3-2+4x)=0
-(x-5)(7x+1)=0
x=5,x=-1/7