4.9t^2-8t-2.3=0

Solution for 4.9t^2-8t-2.3=0 equation:

4.9t^2-8t-2.3=0

a = 4.9; b = -8; c = -2.3;
Δ = b2-4ac
Δ = -82-4·4.9·(-2.3)
Δ = 109.08
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{-(-8)-\sqrt{109.08}}{2*4.9}=\frac{8-\sqrt{109.08}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+\sqrt{109.08}}{2*4.9}=\frac{8+\sqrt{109.08}}{9.8}
$