Fie e elementul neutru.
xoe=x
xoe=(x-√2)(e-√2)+√2=x
x*e-√2e-√2x+2+√2=x
x*e-√2e=x+√2x-2-√2
e(x-√2)=(x+√2x)-(2+√2)
e(x-√2)=x(1+√2)-√2(√2+1)
e(x-√2)=(1+√2)(x-√2) Imparti egalitatea prin x-√2 si obtii
e=1+√2
