0=3.8t-9.8t^2

Solution for 0=3.8t-9.8t^2 equation:

0=3.8t-9.8t^2

We move all terms to the left:

0-(3.8t-9.8t^2)=0

We add all the numbers together, and all the variables

-(3.8t-9.8t^2)=0

We get rid of parentheses

9.8t^2-3.8t=0

a = 9.8; b = -3.8; c = 0;
Δ = b2-4ac
Δ = -3.82-4·9.8·0
Δ = 14.44
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{-(-3.8)-\sqrt{14.44}}{2*9.8}=\frac{3.8-\sqrt{14.44}}{19.6}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3.8)+\sqrt{14.44}}{2*9.8}=\frac{3.8+\sqrt{14.44}}{19.6}
$