0=3+25.5x-4.9x^2

Solution for 0=3+25.5x-4.9x^2 equation:

0=3+25.5x-4.9x^2

We move all terms to the left:

0-(3+25.5x-4.9x^2)=0

We add all the numbers together, and all the variables

-(3+25.5x-4.9x^2)=0

We get rid of parentheses

4.9x^2-25.5x-3=0

a = 4.9; b = -25.5; c = -3;
Δ = b2-4ac
Δ = -25.52-4·4.9·(-3)
Δ = 709.05
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{-(-25.5)-\sqrt{709.05}}{2*4.9}=\frac{25.5-\sqrt{709.05}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25.5)+\sqrt{709.05}}{2*4.9}=\frac{25.5+\sqrt{709.05}}{9.8}
$