-19.8*x^2+20.8*x+3=0

Solution for -19.8*x^2+20.8*x+3=0 equation:

-19.8x^2+20.8x+3=0

a = -19.8; b = 20.8; c = +3;
Δ = b2-4ac
Δ = 20.82-4·(-19.8)·3
Δ = 670.24
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{670.24}}{2*-19.8}=\frac{-20.8-\sqrt{670.24}}{-39.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20.8)+\sqrt{670.24}}{2*-19.8}=\frac{-20.8+\sqrt{670.24}}{-39.6}
$