4.9t2-8t-30=0

Solution for 4.9t2-8t-30=0 equation:

4.9t^2-8t-30=0

a = 4.9; b = -8; c = -30;
Δ = b2-4ac
Δ = -82-4·4.9·(-30)
Δ = 652
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{652}=\sqrt{4*163}=\sqrt{4}*\sqrt{163}=2\sqrt{163}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-2\sqrt{163}}{2*4.9}=\frac{8-2\sqrt{163}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+2\sqrt{163}}{2*4.9}=\frac{8+2\sqrt{163}}{9.8}
$