0=-4.9t^2+27.5t+9.8

Solution for 0=-4.9t^2+27.5t+9.8 equation:

0=-4.9t^2+27.5t+9.8

We move all terms to the left:

0-(-4.9t^2+27.5t+9.8)=0

We add all the numbers together, and all the variables

-(-4.9t^2+27.5t+9.8)=0

We get rid of parentheses

4.9t^2-27.5t-9.8=0

a = 4.9; b = -27.5; c = -9.8;
Δ = b2-4ac
Δ = -27.52-4·4.9·(-9.8)
Δ = 948.33
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{-(-27.5)-\sqrt{948.33}}{2*4.9}=\frac{27.5-\sqrt{948.33}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-27.5)+\sqrt{948.33}}{2*4.9}=\frac{27.5+\sqrt{948.33}}{9.8}
$