H=4+64t+16t^2

Solution for H=4+64t+16t^2 equation:

=4+64H+16H^2

We move all terms to the left:

-(4+64H+16H^2)=0

We get rid of parentheses

-16H^2-64H-4=0

a = -16; b = -64; c = -4;
Δ = b2-4ac
Δ = -642-4·(-16)·(-4)
Δ = 3840
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3840}=\sqrt{256*15}=\sqrt{256}*\sqrt{15}=16\sqrt{15}$
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-64)-16\sqrt{15}}{2*-16}=\frac{64-16\sqrt{15}}{-32}
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-64)+16\sqrt{15}}{2*-16}=\frac{64+16\sqrt{15}}{-32}
$