0=25x-4.9x^2

Solution for 0=25x-4.9x^2 equation:

0=25x-4.9x^2

We move all terms to the left:

0-(25x-4.9x^2)=0

We add all the numbers together, and all the variables

-(25x-4.9x^2)=0

We get rid of parentheses

4.9x^2-25x=0

a = 4.9; b = -25; c = 0;
Δ = b2-4ac
Δ = -252-4·4.9·0
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-25}{2*4.9}=\frac{0}{9.8}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+25}{2*4.9}=\frac{50}{9.8}
=5+1/9.8
$