(x^2 + 2x)^2-2(x+1)^2=1,
(x^2 + 2x)^2-2(x^2+2x+1)-1=0,
(x^2 + 2x)^2-2(x^2+2x)+2-1=0,
(x^2 + 2x)^2-2(x^2+2x)+1=0,
x^2+2x=t,
t^2-2t+1=0,
(t-1)^2=0,
t-1=0,
t=1,
x^2+2x=1,
x^2+2x-1=0,
D1=2,
x1=-1-√2,
x2=-1+√2
