-4.9t2+33.6t+4.9=0

Solution for -4.9t2+33.6t+4.9=0 equation:

-4.9t^2+33.6t+4.9=0

a = -4.9; b = 33.6; c = +4.9;
Δ = b2-4ac
Δ = 33.62-4·(-4.9)·4.9
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(33.6)-35}{2*-4.9}=\frac{-68.6}{-9.8}
=6+1/1
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(33.6)+35}{2*-4.9}=\frac{1.4}{-9.8}
=-1/7
$