80-4.9t^2=0

Solution for 80-4.9t^2=0 equation:

80-4.9t^2=0

a = -4.9; b = 0; c = +80;
Δ = b2-4ac
Δ = 02-4·(-4.9)·80
Δ = 1568
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:

$\sqrt{\Delta}=\sqrt{1568}=\sqrt{784*2}=\sqrt{784}*\sqrt{2}=28\sqrt{2}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-28\sqrt{2}}{2*-4.9}=\frac{0-28\sqrt{2}}{-9.8}
=-\frac{28\sqrt{2}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+28\sqrt{2}}{2*-4.9}=\frac{0+28\sqrt{2}}{-9.8}
=\frac{28\sqrt{2}}{-9.8}
$