The money to be spent for the welfare of the employees of a firm is proportional to the rate of change of its total revenue (marginal revenue). If the total revenue (in rupees) received from the sale of x units of a product is given by R(x) =3x² +36x + 5, find the marginal revenue when x = 5, and write which value does the question indicate.

Given, total revenue function for sale of x units of a product is

R(x) = 3x² +36x + 5

Marginal revenue is given by the derivative of R(x).

Let M(x) represents the marginal revenue function for sale of x units of a product.

∴ M(x) =

∴ M(x) = 6x + 36

This equation indicates the additional revenue generated for sale of an additional unit of product x also we can say that it represents the change in total revenue with respect to change in number of units sold.

And, M(5) = 6(5)+36 = 30+36 = 66