-9q^2-72q=0

Solution for -9q^2-72q=0 equation:

-9q^2-72q=0

a = -9; b = -72; c = 0;
Δ = b2-4ac
Δ = -722-4·(-9)·0
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-72}{2*-9}=\frac{0}{-18}
=0
$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+72}{2*-9}=\frac{144}{-18}
=-8
$