4.9*x^2+20.8*x+3=0

Solution for 4.9*x^2+20.8*x+3=0 equation:

4.9x^2+20.8x+3=0

a = 4.9; b = 20.8; c = +3;
Δ = b2-4ac
Δ = 20.82-4·4.9·3
Δ = 373.84
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{-(20.8)-\sqrt{373.84}}{2*4.9}=\frac{-20.8-\sqrt{373.84}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20.8)+\sqrt{373.84}}{2*4.9}=\frac{-20.8+\sqrt{373.84}}{9.8}
$