R(x)=36000-6x^2

Solution for R(x)=36000-6x^2 equation:

(R)=36000-6R^2

We move all terms to the left:

(R)-(36000-6R^2)=0

We get rid of parentheses

6R^2+R-36000=0

a = 6; b = 1; c = -36000;
Δ = b2-4ac
Δ = 12-4·6·(-36000)
Δ = 864001
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{864001}}{2*6}=\frac{-1-\sqrt{864001}}{12}
$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{864001}}{2*6}=\frac{-1+\sqrt{864001}}{12}
$