4.9x^2-19.6x-20=0

Solution for 4.9x^2-19.6x-20=0 equation:

4.9x^2-19.6x-20=0

a = 4.9; b = -19.6; c = -20;
Δ = b2-4ac
Δ = -19.62-4·4.9·(-20)
Δ = 776.16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-19.6)-\sqrt{776.16}}{2*4.9}=\frac{19.6-\sqrt{776.16}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-19.6)+\sqrt{776.16}}{2*4.9}=\frac{19.6+\sqrt{776.16}}{9.8}
$