0=-16x^2-20x+400

Solution for 0=-16x^2-20x+400 equation:

0=-16x^2-20x+400

We move all terms to the left:

0-(-16x^2-20x+400)=0

We add all the numbers together, and all the variables

-(-16x^2-20x+400)=0

We get rid of parentheses

16x^2+20x-400=0

a = 16; b = 20; c = -400;
Δ = b2-4ac
Δ = 202-4·16·(-400)
Δ = 26000
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:

$\sqrt{\Delta}=\sqrt{26000}=\sqrt{400*65}=\sqrt{400}*\sqrt{65}=20\sqrt{65}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-20\sqrt{65}}{2*16}=\frac{-20-20\sqrt{65}}{32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+20\sqrt{65}}{2*16}=\frac{-20+20\sqrt{65}}{32}
$