X2+4x=720

Solution for X2+4x=720 equation:

X2+4X=720

We move all terms to the left:

X2+4X-(720)=0

We add all the numbers together, and all the variables

X^2+4X-720=0

a = 1; b = 4; c = -720;
Δ = b2-4ac
Δ = 42-4·1·(-720)
Δ = 2896
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:

$\sqrt{\Delta}=\sqrt{2896}=\sqrt{16*181}=\sqrt{16}*\sqrt{181}=4\sqrt{181}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{181}}{2*1}=\frac{-4-4\sqrt{181}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{181}}{2*1}=\frac{-4+4\sqrt{181}}{2}
$