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

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

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

We multiply parentheses ..

(+2x^2-10x+9x-45)=0

We get rid of parentheses

2x^2-10x+9x-45=0

We add all the numbers together, and all the variables

2x^2-1x-45=0

a = 2; b = -1; c = -45;
Δ = b2-4ac
Δ = -12-4·2·(-45)
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-19}{2*2}=\frac{-18}{4}
=-4+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+19}{2*2}=\frac{20}{4}
=5
$