720=2x^2+12x-36

Solution for 720=2x^2+12x-36 equation:

720=2x^2+12x-36

We move all terms to the left:

720-(2x^2+12x-36)=0

We get rid of parentheses

-2x^2-12x+36+720=0

We add all the numbers together, and all the variables

-2x^2-12x+756=0

a = -2; b = -12; c = +756;
Δ = b2-4ac
Δ = -122-4·(-2)·756
Δ = 6192
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:

$\sqrt{\Delta}=\sqrt{6192}=\sqrt{144*43}=\sqrt{144}*\sqrt{43}=12\sqrt{43}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-12\sqrt{43}}{2*-2}=\frac{12-12\sqrt{43}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+12\sqrt{43}}{2*-2}=\frac{12+12\sqrt{43}}{-4}
$