H=-4.9t^2+80t+2

Solution for H=-4.9t^2+80t+2 equation:

=-4.9H^2+80H+2

We move all terms to the left:

-(-4.9H^2+80H+2)=0

We get rid of parentheses

4.9H^2-80H-2=0

a = 4.9; b = -80; c = -2;
Δ = b2-4ac
Δ = -802-4·4.9·(-2)
Δ = 6439.2
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-\sqrt{6439.2}}{2*4.9}=\frac{80-\sqrt{6439.2}}{9.8}
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+\sqrt{6439.2}}{2*4.9}=\frac{80+\sqrt{6439.2}}{9.8}
$