4.9t^2-6.647t-2.5=0

Solution for 4.9t^2-6.647t-2.5=0 equation:

4.9t^2-6.647t-2.5=0

a = 4.9; b = -6.647; c = -2.5;
Δ = b2-4ac
Δ = -6.6472-4·4.9·(-2.5)
Δ = 93.182609
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{-(-6.647)-\sqrt{93.182609}}{2*4.9}=\frac{6.647-\sqrt{93.182609}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6.647)+\sqrt{93.182609}}{2*4.9}=\frac{6.647+\sqrt{93.182609}}{9.8}
$