0=4.9t^2-5t-1.2

Solution for 0=4.9t^2-5t-1.2 equation:

0=4.9t^2-5t-1.2

We move all terms to the left:

0-(4.9t^2-5t-1.2)=0

We add all the numbers together, and all the variables

-(4.9t^2-5t-1.2)=0

We get rid of parentheses

-4.9t^2+5t+1.2=0

a = -4.9; b = 5; c = +1.2;
Δ = b2-4ac
Δ = 52-4·(-4.9)·1.2
Δ = 48.52
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{-(5)-\sqrt{48.52}}{2*-4.9}=\frac{-5-\sqrt{48.52}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{48.52}}{2*-4.9}=\frac{-5+\sqrt{48.52}}{-9.8}
$