(6x-20)(6x+10)=180

Solution for (6x-20)(6x+10)=180 equation:

(6x-20)(6x+10)=180

We move all terms to the left:

(6x-20)(6x+10)-(180)=0

We multiply parentheses ..

(+36x^2+60x-120x-200)-180=0

We get rid of parentheses

36x^2+60x-120x-200-180=0

We add all the numbers together, and all the variables

36x^2-60x-380=0

a = 36; b = -60; c = -380;
Δ = b2-4ac
Δ = -602-4·36·(-380)
Δ = 58320
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{58320}=\sqrt{11664*5}=\sqrt{11664}*\sqrt{5}=108\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-108\sqrt{5}}{2*36}=\frac{60-108\sqrt{5}}{72}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+108\sqrt{5}}{2*36}=\frac{60+108\sqrt{5}}{72}
$