-9x^2-8x-1=0

Solution for -9x^2-8x-1=0 equation:

-9x^2-8x-1=0

a = -9; b = -8; c = -1;
Δ = b2-4ac
Δ = -82-4·(-9)·(-1)
Δ = 28
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{28}=\sqrt{4*7}=\sqrt{4}*\sqrt{7}=2\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-2\sqrt{7}}{2*-9}=\frac{8-2\sqrt{7}}{-18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+2\sqrt{7}}{2*-9}=\frac{8+2\sqrt{7}}{-18}
$