0=15-16.3392x-4.9x^2

Solution for 0=15-16.3392x-4.9x^2 equation:

0=15-16.3392x-4.9x^2

We move all terms to the left:

0-(15-16.3392x-4.9x^2)=0

We add all the numbers together, and all the variables

-(15-16.3392x-4.9x^2)=0

We get rid of parentheses

4.9x^2+16.3392x-15=0

a = 4.9; b = 16.3392; c = -15;
Δ = b2-4ac
Δ = 16.33922-4·4.9·(-15)
Δ = 560.96945664
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{-(16.3392)-\sqrt{560.96945664}}{2*4.9}=\frac{-16.3392-\sqrt{560.96945664}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16.3392)+\sqrt{560.96945664}}{2*4.9}=\frac{-16.3392+\sqrt{560.96945664}}{9.8}
$