(2m+5)(m-9)=0

Solution for (2m+5)(m-9)=0 equation:

(2m+5)(m-9)=0

We multiply parentheses ..

(+2m^2-18m+5m-45)=0

We get rid of parentheses

2m^2-18m+5m-45=0

We add all the numbers together, and all the variables

2m^2-13m-45=0

a = 2; b = -13; c = -45;
Δ = b2-4ac
Δ = -132-4·2·(-45)
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-23}{2*2}=\frac{-10}{4}
=-2+1/2
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+23}{2*2}=\frac{36}{4}
=9
$