-8m(2m+9)=0

Solution for -8m(2m+9)=0 equation:

-8m(2m+9)=0

We multiply parentheses

-16m^2-72m=0

a = -16; b = -72; c = 0;
Δ = b2-4ac
Δ = -722-4·(-16)·0
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-72}{2*-16}=\frac{0}{-32}
=0
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+72}{2*-16}=\frac{144}{-32}
=-4+1/2
$