R(x)=4x-0.01x^2

Solution for R(x)=4x-0.01x^2 equation:

(R)=4R-0.01R^2

We move all terms to the left:

(R)-(4R-0.01R^2)=0

We get rid of parentheses

0.01R^2-4R+R=0

We add all the numbers together, and all the variables

0.01R^2-3R=0

a = 0.01; b = -3; c = 0;
Δ = b2-4ac
Δ = -32-4·0.01·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-3}{2*0.01}=\frac{0}{0.02}
=0
$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+3}{2*0.01}=\frac{6}{0.02}
=300
$