-8b^2-18b-9=0

Solution for -8b^2-18b-9=0 equation:

-8b^2-18b-9=0

a = -8; b = -18; c = -9;
Δ = b2-4ac
Δ = -182-4·(-8)·(-9)
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-6}{2*-8}=\frac{12}{-16}
=-3/4
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+6}{2*-8}=\frac{24}{-16}
=-1+1/2
$