2（x^2-2x+1)-1=02(x-1)²=1x-1=±（1/2)^(1/2)x=1±（1/2)^(1/2)
2x^2-4x+1=0 x^2-2x+1/2=0 (x-1)^2=1/2 x-1=±√2/2 x1=1=±√2/2 x2=1-√2/2
