0=4+120x-4.9x^2

Solution for 0=4+120x-4.9x^2 equation:

0=4+120x-4.9x^2

We move all terms to the left:

0-(4+120x-4.9x^2)=0

We add all the numbers together, and all the variables

-(4+120x-4.9x^2)=0

We get rid of parentheses

4.9x^2-120x-4=0

a = 4.9; b = -120; c = -4;
Δ = b2-4ac
Δ = -1202-4·4.9·(-4)
Δ = 14478.4
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{-(-120)-\sqrt{14478.4}}{2*4.9}=\frac{120-\sqrt{14478.4}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-120)+\sqrt{14478.4}}{2*4.9}=\frac{120+\sqrt{14478.4}}{9.8}
$