4.8=14.5t-4.9t^2

Solution for 4.8=14.5t-4.9t^2 equation:

4.8=14.5t-4.9t^2

We move all terms to the left:

4.8-(14.5t-4.9t^2)=0

We get rid of parentheses

4.9t^2-14.5t+4.8=0

a = 4.9; b = -14.5; c = +4.8;
Δ = b2-4ac
Δ = -14.52-4·4.9·4.8
Δ = 116.17
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{-(-14.5)-\sqrt{116.17}}{2*4.9}=\frac{14.5-\sqrt{116.17}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14.5)+\sqrt{116.17}}{2*4.9}=\frac{14.5+\sqrt{116.17}}{9.8}
$