数学简单``急～！！谢谢～！
1.[7x-1]^2=4x^2
2.4x^2=12x
3.9x^2=[x-1]^2
4.[2x-1]^2=-8x
要点过程~！谢谢~！
参考答案:1.[7x-1]^2=4x^2
45x^2-14x-1=0
(5x-1)(9x-1)=0
x=1/5,x=1/9
2.4x^2=12x
x(x-3)=0
x=0,x=3
3.9x^2=[x-1]^2
8x^2+2x-1=0
(4x-1)(2x-1)=0
x=1/4,x=1/2
4.[2x-1]^2=-8x
4x^2+4x+1=0
(2x+1)^2=0
x1=x2=-1/2