D=144t-16t^2

Solution for D=144t-16t^2 equation:

=144D-16D^2

We move all terms to the left:

-(144D-16D^2)=0

We get rid of parentheses

16D^2-144D=0

a = 16; b = -144; c = 0;
Δ = b2-4ac
Δ = -1442-4·16·0
Δ = 20736
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{20736}=144$
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-144)-144}{2*16}=\frac{0}{32}
=0
$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-144)+144}{2*16}=\frac{288}{32}
=9
$