Question

x patrat-4=0 (trebuie sa dea S={-2;2} )

Answer 1

x² -4=0
(x -2 ) · ( x+2)=0
x-2=0          x=2
x+2=0         x=-2

Answer 2

X patrat -4=0 X patrat = 0 plus 4 X patrat = 4 X= radical din 2 X=2 X€{-2;2}