450=4.9t^2

Solution for 450=4.9t^2 equation:

450=4.9t^2

We move all terms to the left:

450-(4.9t^2)=0

We get rid of parentheses

-4.9t^2+450=0

a = -4.9; b = 0; c = +450;
Δ = b2-4ac
Δ = 02-4·(-4.9)·450
Δ = 8820
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:

$\sqrt{\Delta}=\sqrt{8820}=\sqrt{1764*5}=\sqrt{1764}*\sqrt{5}=42\sqrt{5}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-42\sqrt{5}}{2*-4.9}=\frac{0-42\sqrt{5}}{-9.8}
=-\frac{42\sqrt{5}}{-9.8}
=-\frac{14\sqrt{5}}{-3.26666666667}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+42\sqrt{5}}{2*-4.9}=\frac{0+42\sqrt{5}}{-9.8}
=\frac{42\sqrt{5}}{-9.8}
=\frac{14\sqrt{5}}{-3.26666666667}
$