810=-490t^2+1260

Solution for 810=-490t^2+1260 equation:

810=-490t^2+1260

We move all terms to the left:

810-(-490t^2+1260)=0

We get rid of parentheses

490t^2-1260+810=0

We add all the numbers together, and all the variables

490t^2-450=0

a = 490; b = 0; c = -450;
Δ = b2-4ac
Δ = 02-4·490·(-450)
Δ = 882000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{882000}=\sqrt{176400*5}=\sqrt{176400}*\sqrt{5}=420\sqrt{5}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-420\sqrt{5}}{2*490}=\frac{0-420\sqrt{5}}{980}
=-\frac{420\sqrt{5}}{980}
=-\frac{3\sqrt{5}}{7}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+420\sqrt{5}}{2*490}=\frac{0+420\sqrt{5}}{980}
=\frac{420\sqrt{5}}{980}
=\frac{3\sqrt{5}}{7}
$