2=-4.9t^2+4.5

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

2=-4.9t^2+4.5

We move all terms to the left:

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

We get rid of parentheses

4.9t^2-4.5+2=0

We add all the numbers together, and all the variables

4.9t^2-2.5=0

a = 4.9; b = 0; c = -2.5;
Δ = b2-4ac
Δ = 02-4·4.9·(-2.5)
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-7}{2*4.9}=\frac{-7}{9.8}
=-7/9.8
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+7}{2*4.9}=\frac{7}{9.8}
=7/9.8
$