-20b^2-9b+18=9

Solution for -20b^2-9b+18=9 equation:

-20b^2-9b+18=9

We move all terms to the left:

-20b^2-9b+18-(9)=0

We add all the numbers together, and all the variables

-20b^2-9b+9=0

a = -20; b = -9; c = +9;
Δ = b2-4ac
Δ = -92-4·(-20)·9
Δ = 801
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{801}=\sqrt{9*89}=\sqrt{9}*\sqrt{89}=3\sqrt{89}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-3\sqrt{89}}{2*-20}=\frac{9-3\sqrt{89}}{-40}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+3\sqrt{89}}{2*-20}=\frac{9+3\sqrt{89}}{-40}
$