0=4.5t-4.9t^2

Solution for 0=4.5t-4.9t^2 equation:

0=4.5t-4.9t^2

We move all terms to the left:

0-(4.5t-4.9t^2)=0

We add all the numbers together, and all the variables

-(4.5t-4.9t^2)=0

We get rid of parentheses

4.9t^2-4.5t=0

a = 4.9; b = -4.5; c = 0;
Δ = b2-4ac
Δ = -4.52-4·4.9·0
Δ = 20.25
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{-(-4.5)-\sqrt{20.25}}{2*4.9}=\frac{4.5-\sqrt{20.25}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4.5)+\sqrt{20.25}}{2*4.9}=\frac{4.5+\sqrt{20.25}}{9.8}
$