-16x^2+80x+220=0

Solution for -16x^2+80x+220=0 equation:

-16x^2+80x+220=0

a = -16; b = 80; c = +220;
Δ = b2-4ac
Δ = 802-4·(-16)·220
Δ = 20480
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:

$\sqrt{\Delta}=\sqrt{20480}=\sqrt{4096*5}=\sqrt{4096}*\sqrt{5}=64\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-64\sqrt{5}}{2*-16}=\frac{-80-64\sqrt{5}}{-32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+64\sqrt{5}}{2*-16}=\frac{-80+64\sqrt{5}}{-32}
$