(5x+45)(x-30)=0

Solution for (5x+45)(x-30)=0 equation:

(5x+45)(x-30)=0

We multiply parentheses ..

(+5x^2-150x+45x-1350)=0

We get rid of parentheses

5x^2-150x+45x-1350=0

We add all the numbers together, and all the variables

5x^2-105x-1350=0

a = 5; b = -105; c = -1350;
Δ = b2-4ac
Δ = -1052-4·5·(-1350)
Δ = 38025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{38025}=195$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-105)-195}{2*5}=\frac{-90}{10}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-105)+195}{2*5}=\frac{300}{10}
=30
$