O=-16t^2+400

Solution for O=-16t^2+400 equation:

=-16O^2+400

We move all terms to the left:

-(-16O^2+400)=0

We get rid of parentheses

16O^2-400=0

a = 16; b = 0; c = -400;
Δ = b2-4ac
Δ = 02-4·16·(-400)
Δ = 25600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$O_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$O_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25600}=160$
$O_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-160}{2*16}=\frac{-160}{32}
=-5
$
$O_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+160}{2*16}=\frac{160}{32}
=5
$