1.4t^2-9.8t-4.9=0

Solution for 1.4t^2-9.8t-4.9=0 equation:

1.4t^2-9.8t-4.9=0

a = 1.4; b = -9.8; c = -4.9;
Δ = b2-4ac
Δ = -9.82-4·1.4·(-4.9)
Δ = 123.48
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{-(-9.8)-\sqrt{123.48}}{2*1.4}=\frac{9.8-\sqrt{123.48}}{2.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9.8)+\sqrt{123.48}}{2*1.4}=\frac{9.8+\sqrt{123.48}}{2.8}
$