2x^2-4x-1=0 2(x^2-2x)-1=0 2[(x^2-2x+1)-1]-1=0 2[(x-1)^2-1]-1=0 2(X-1)^2-3=0 2(X-1)^2=3 (X-1)^2=3/2 X-1=根号6/2 x1=根号6/2 +1 X-1=-根号6/2 x2=1-根号6/2