\[y = - \sqrt{x};\]
\[x + 3y = 0\]
\[3y = - x\]
\[y = - \frac{1}{3}\text{x.}\]
\[x = 0;x = 9.\]
\[y = 0;y = - 3.\]
\[Ответ:(0;0);(9; - 3).\]