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 1
1 Find the rate of change of the area of a circle with respect to its radius r when
(a)
r = 3 cm
(b)
r = 4 cm
2