H=90t+16t^2

Solution for H=90t+16t^2 equation:

=90H+16H^2

We move all terms to the left:

-(90H+16H^2)=0

We get rid of parentheses

-16H^2-90H=0

a = -16; b = -90; c = 0;
Δ = b2-4ac
Δ = -902-4·(-16)·0
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-90}{2*-16}=\frac{0}{-32}
=0
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+90}{2*-16}=\frac{180}{-32}
=-5+5/8
$