Question 2: Optimization of multivariate functions (14 marks) A firm sells two products which are partial substitutes for each other. If the price of one product increases then the demand for the other substitute product rises. The prices of the two products (in Rand) are P] and P2 and their respective demand functions are Q1 = 517 - 3.5P, + 0.8P2 and Q2 = 770 -4.4P2 + 1.4P, 1. (2 marks) Derive the total revenue (TR) of the firm. 2. (10 marks) What price should the firm charge for each product to maximize its total revenue? Show all steps. 3. (2 marks) What is the maximum total revenue TR"? Hint: For this question it is more convenient to express total revenue as a function of price rather than quantity