\[f(x) = \sqrt{x^{2} + 3}\]
\[\sqrt{x^{2} + 3} = 0\]
\[Ответ:нулей\ нет.\]
\[7)\ f(x) = (x + 1)\sqrt{x}\]
\[(x + 1)\sqrt{x} = 0\]
\[x = 0,\ \ \ x = - 1,\ \ \ x \geq 0\]
\[Ответ:0.\]