Question

$9x {}^{2} - 2x - 1 = 0$need the solve

Answer 1

The mistake is that since a=9, the 2a in the denominator should be 2x9 and not 2

$\begin{gathered} x=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a} \\ \\ x=\frac{2\pm\sqrt[]{(-2)^2-4(9)(-1)}}{2(9)} \end{gathered}$