（2x-1）²-x²-4x-4=0
（2x-1）²-(x²+4x+4)=0
（2x-1）²-(x+2)²=0
(2x-1-x-2)(2x-1+x+2)=0
(x-3)(3x+1)=0
x1=3 x2=-1/3