0=20+3x-4,9x^2

Solution for 0=20+3x-4,9x^2 equation:

0=20+3x-4.9x^2

We move all terms to the left:

0-(20+3x-4.9x^2)=0

We add all the numbers together, and all the variables

-(20+3x-4.9x^2)=0

We get rid of parentheses

4.9x^2-3x-20=0

a = 4.9; b = -3; c = -20;
Δ = b2-4ac
Δ = -32-4·4.9·(-20)
Δ = 401
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{-(-3)-\sqrt{401}}{2*4.9}=\frac{3-\sqrt{401}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+\sqrt{401}}{2*4.9}=\frac{3+\sqrt{401}}{9.8}
$