Răspuns :
(a-b)(a+b)=(a)^2-(b)^2 (a la puterea a doua minus b la puterea a doua)
(x-5)(x+5)=(x)^2-25
(x)^2-25=0
(x)^2=25
x=sqrt(25) (radical din 25)
x= +/- 5 (plus sau minus 5)
(x-5)(x+5)=(x)^2-25
(x)^2-25=0
(x)^2=25
x=sqrt(25) (radical din 25)
x= +/- 5 (plus sau minus 5)