300000000-2000x-0.01x^2=0

Solution for 300000000-2000x-0.01x^2=0 equation:

300000000-2000x-0.01x^2=0

a = -0.01; b = -2000; c = +300000000;
Δ = b2-4ac
Δ = -20002-4·(-0.01)·300000000
Δ = 16000000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16000000}=4000$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2000)-4000}{2*-0.01}=\frac{-2000}{-0.02}
=+100000
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2000)+4000}{2*-0.01}=\frac{6000}{-0.02}
=-300000
$