-16x^2+80x+25=0

Solution for -16x^2+80x+25=0 equation:

-16x^2+80x+25=0

a = -16; b = 80; c = +25;
Δ = b2-4ac
Δ = 802-4·(-16)·25
Δ = 8000
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:

$\sqrt{\Delta}=\sqrt{8000}=\sqrt{1600*5}=\sqrt{1600}*\sqrt{5}=40\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-40\sqrt{5}}{2*-16}=\frac{-80-40\sqrt{5}}{-32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+40\sqrt{5}}{2*-16}=\frac{-80+40\sqrt{5}}{-32}
$