2.6=400-16t^2

Solution for 2.6=400-16t^2 equation:

2.6=400-16t^2

We move all terms to the left:

2.6-(400-16t^2)=0

We get rid of parentheses

16t^2-400+2.6=0

We add all the numbers together, and all the variables

16t^2-397.4=0

a = 16; b = 0; c = -397.4;
Δ = b2-4ac
Δ = 02-4·16·(-397.4)
Δ = 25433.6
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{25433.6}}{2*16}=\frac{0-\sqrt{25433.6}}{32}
=-\frac{\sqrt{}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{25433.6}}{2*16}=\frac{0+\sqrt{25433.6}}{32}
=\frac{\sqrt{}}{32}
$