H=-4.9t^2+17t+2.2

Solution for H=-4.9t^2+17t+2.2 equation:

=-4.9H^2+17H+2.2

We move all terms to the left:

-(-4.9H^2+17H+2.2)=0

We get rid of parentheses

4.9H^2-17H-2.2=0

a = 4.9; b = -17; c = -2.2;
Δ = b2-4ac
Δ = -172-4·4.9·(-2.2)
Δ = 332.12
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{-(-17)-\sqrt{332.12}}{2*4.9}=\frac{17-\sqrt{332.12}}{9.8}
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-17)+\sqrt{332.12}}{2*4.9}=\frac{17+\sqrt{332.12}}{9.8}
$