4x^2-16x-720=0

Solution for 4x^2-16x-720=0 equation:

4x^2-16x-720=0

a = 4; b = -16; c = -720;
Δ = b2-4ac
Δ = -162-4·4·(-720)
Δ = 11776
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:

$\sqrt{\Delta}=\sqrt{11776}=\sqrt{256*46}=\sqrt{256}*\sqrt{46}=16\sqrt{46}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-16\sqrt{46}}{2*4}=\frac{16-16\sqrt{46}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+16\sqrt{46}}{2*4}=\frac{16+16\sqrt{46}}{8}
$