1920=16t^2

Solution for 1920=16t^2 equation:

1920=16t^2

We move all terms to the left:

1920-(16t^2)=0

a = -16; b = 0; c = +1920;
Δ = b2-4ac
Δ = 02-4·(-16)·1920
Δ = 122880
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:

$\sqrt{\Delta}=\sqrt{122880}=\sqrt{4096*30}=\sqrt{4096}*\sqrt{30}=64\sqrt{30}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-64\sqrt{30}}{2*-16}=\frac{0-64\sqrt{30}}{-32}
=-\frac{64\sqrt{30}}{-32}
=-\frac{2\sqrt{30}}{-1}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+64\sqrt{30}}{2*-16}=\frac{0+64\sqrt{30}}{-32}
=\frac{64\sqrt{30}}{-32}
=\frac{2\sqrt{30}}{-1}
$