^ inseamna la putere
(x-1)^2=x^2-2x-1
x^2-2x-1=3
x^2-2x=4
x^2-2x-4=0, a=1,b= -2,c= -4
delta=b^2-4ac
delta=4-4×1×(-4)
delta=4+16=20
x1 si x2=-b±√delta supra 2a
x1= 2+2√5/2=2(1+√5)/2=1+√5
x2=2-2√5/2=2(1-√5)/2=1-√5
deci x={1+√5,1-√5}
suma elementelor este
1+√5+1-√5=2
