\[y = - 9x^{2} + 1\]
\[- 9x^{2} + 1 = 0\]
\[- 9x^{2} = - 1\]
\[9x^{2} = 1\]
\[x^{2} = \frac{1}{9}\]
\[x = \pm \frac{1}{3}.\]