R(x)=366x-0.9x^2

Solution for R(x)=366x-0.9x^2 equation:

(R)=366R-0.9R^2

We move all terms to the left:

(R)-(366R-0.9R^2)=0

We get rid of parentheses

0.9R^2-366R+R=0

We add all the numbers together, and all the variables

0.9R^2-365R=0

a = 0.9; b = -365; c = 0;
Δ = b2-4ac
Δ = -3652-4·0.9·0
Δ = 133225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{133225}=365$
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-365)-365}{2*0.9}=\frac{0}{1.8}
=0
$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-365)+365}{2*0.9}=\frac{730}{1.8}
=405+1/1.8
$