4.9t2-2.2t-3.4=0,

Solution for 4.9t2-2.2t-3.4=0, equation:

4.9t^2-2.2t-3.4=0.

a = 4.9; b = -2.2; c = -3.4;
Δ = b2-4ac
Δ = -2.22-4·4.9·(-3.4)
Δ = 71.48
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{-(-2.2)-\sqrt{71.48}}{2*4.9}=\frac{2.2-\sqrt{71.48}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2.2)+\sqrt{71.48}}{2*4.9}=\frac{2.2+\sqrt{71.48}}{9.8}
$