Răspuns:
x = 11
Explicație pas cu pas:
[tex]\frac{x}{\sqrt{15}}= \frac{\sqrt{5}}{\sqrt{3}} + \frac{2\sqrt{3}}{\sqrt{5}} \\\\\frac{x}{\sqrt{15}}= \frac{\sqrt{5}*\sqrt{5}}{\sqrt{3}*\sqrt{5}} + \frac{2\sqrt{3}*\sqrt{3}}{\sqrt{5}*\sqrt{3}}\\\\\frac{x}{\sqrt{15}}= \frac{5}{\sqrt{5*3}} +\frac{2*3}{\sqrt{5*3}} \\\\\frac{x}{\sqrt{15}}=\frac{5+6}{\sqrt{15}}=\frac{11}{\sqrt{15}}\\\\x=11[/tex]
