X=15000-300x^2

Solution for X=15000-300x^2 equation:

X=15000-300X^2

We move all terms to the left:

X-(15000-300X^2)=0

We get rid of parentheses

300X^2+X-15000=0

a = 300; b = 1; c = -15000;
Δ = b2-4ac
Δ = 12-4·300·(-15000)
Δ = 18000001
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{-(1)-\sqrt{18000001}}{2*300}=\frac{-1-\sqrt{18000001}}{600}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{18000001}}{2*300}=\frac{-1+\sqrt{18000001}}{600}
$