16=-16t^2+256t

Solution for 16=-16t^2+256t equation:

16=-16t^2+256t

We move all terms to the left:

16-(-16t^2+256t)=0

We get rid of parentheses

16t^2-256t+16=0

a = 16; b = -256; c = +16;
Δ = b2-4ac
Δ = -2562-4·16·16
Δ = 64512
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{64512}=\sqrt{9216*7}=\sqrt{9216}*\sqrt{7}=96\sqrt{7}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-256)-96\sqrt{7}}{2*16}=\frac{256-96\sqrt{7}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-256)+96\sqrt{7}}{2*16}=\frac{256+96\sqrt{7}}{32}
$