The total revenue in Rupees received from the sale of x units of a product is given by R(x) = 13x² + 26x + 15.  Find the marginal revenue when x = 7.

Marginal revenue is the rate of change of total revenue with respect to the number of units sold.

∴ Marginal Revenue (MR) θ = 0 = 13(2x) + 26 = 26x + 26

When x = 7,

MR = 26(7) + 26 = 182 + 26 = 208

Hence, the required marginal revenue is Rs 208.