The demand function for a certain product is represented by the equation: $p = 20 + 5x-3x^2$, where $x$ is the number of units demanded and $p$ is the price per unit (in Rs.),then the marginal revenue when 2 units are sold, is:

Rs.4

The correct answer is Option (2) → Rs.4 **

Demand function: $p=20+5x-3x^{2}$

Total revenue: $R=xp=x(20+5x-3x^{2})=20x+5x^{2}-3x^{3}$

Marginal revenue: $\frac{dR}{dx}=20+10x-9x^{2}$

At $x=2$:

$MR=20+10(2)-9(2^{2})$

$MR=20+20-36$

$MR=4$

The marginal revenue when 2 units are sold is $4$.