Question

Se considera nr.reale a=(2-radical5)totul in radical la putera a2+ (2+radical5)totul in radical la puterea a 2 aratati ca a=2 radical din 5

Answer 1

[tex]a= \sqrt{(2- \sqrt{5})^2 } +\sqrt{(2+ \sqrt{5})^2 } \\ a=|2- \sqrt{5}|+|2+ \sqrt{5}|\\ a=\sqrt{5}-2+2+ \sqrt{5}\\ a=2\sqrt{5}[/tex]