15(m-9)(m+3)=0

Solution for 15(m-9)(m+3)=0 equation:

15(m-9)(m+3)=0

We multiply parentheses ..

15(+m^2+3m-9m-27)=0

We multiply parentheses

15m^2+45m-135m-405=0

We add all the numbers together, and all the variables

15m^2-90m-405=0

a = 15; b = -90; c = -405;
Δ = b2-4ac
Δ = -902-4·15·(-405)
Δ = 32400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{32400}=180$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-180}{2*15}=\frac{-90}{30}
=-3
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+180}{2*15}=\frac{270}{30}
=9
$