0=4.9t^2-2t-1

Solution for 0=4.9t^2-2t-1 equation:

0=4.9t^2-2t-1

We move all terms to the left:

0-(4.9t^2-2t-1)=0

We add all the numbers together, and all the variables

-(4.9t^2-2t-1)=0

We get rid of parentheses

-4.9t^2+2t+1=0

a = -4.9; b = 2; c = +1;
Δ = b2-4ac
Δ = 22-4·(-4.9)·1
Δ = 23.6
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{-(2)-\sqrt{23.6}}{2*-4.9}=\frac{-2-\sqrt{23.6}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+\sqrt{23.6}}{2*-4.9}=\frac{-2+\sqrt{23.6}}{-9.8}
$