720=80x^2

Solution for 720=80x^2 equation:

720=80x^2

We move all terms to the left:

720-(80x^2)=0

a = -80; b = 0; c = +720;
Δ = b2-4ac
Δ = 02-4·(-80)·720
Δ = 230400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{230400}=480$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-480}{2*-80}=\frac{-480}{-160}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+480}{2*-80}=\frac{480}{-160}
=-3
$