(3x+20)(x-6)=0

Solution for (3x+20)(x-6)=0 equation:

(3x+20)(x-6)=0

We multiply parentheses ..

(+3x^2-18x+20x-120)=0

We get rid of parentheses

3x^2-18x+20x-120=0

We add all the numbers together, and all the variables

3x^2+2x-120=0

a = 3; b = 2; c = -120;
Δ = b2-4ac
Δ = 22-4·3·(-120)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-38}{2*3}=\frac{-40}{6}
=-6+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+38}{2*3}=\frac{36}{6}
=6
$