Example 6 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, where by
marginal revenue we mean the rate of change of total revenue with respect to the
number of items sold at an instant Solution Since marginal revenue is the rate of change of total revenue with respect to
the number of units sold, we have
Marginal Revenue
(MR) =
R
6
36
d
dx =x
+
When
x = 5, MR = 6(5) + 36 = 66
Hence, the required marginal revenue is ` 66 EXERCISE 6