H=-16t^2+25t+90

Solution for H=-16t^2+25t+90 equation:

=-16H^2+25H+90

We move all terms to the left:

-(-16H^2+25H+90)=0

We get rid of parentheses

16H^2-25H-90=0

a = 16; b = -25; c = -90;
Δ = b2-4ac
Δ = -252-4·16·(-90)
Δ = 6385
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{-(-25)-\sqrt{6385}}{2*16}=\frac{25-\sqrt{6385}}{32}
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+\sqrt{6385}}{2*16}=\frac{25+\sqrt{6385}}{32}
$