4,9t^2-1,5t-1,5=0

Solution for 4,9t^2-1,5t-1,5=0 equation:

4.9t^2-1.5t-1.5=0

a = 4.9; b = -1.5; c = -1.5;
Δ = b2-4ac
Δ = -1.52-4·4.9·(-1.5)
Δ = 31.65
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{-(-1.5)-\sqrt{31.65}}{2*4.9}=\frac{1.5-\sqrt{31.65}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.5)+\sqrt{31.65}}{2*4.9}=\frac{1.5+\sqrt{31.65}}{9.8}
$