integration question

(a) ('3) x3 Given that f(x) =?5x2 +21x+32 (i) Find the critical number(s) of the mction f(x}. [4 marks] (ii) Find the extremum point(s) of f(x). [5 marks] Oil spill from a ruptured tanker spreads in a circle whose radius increases at a constant rate of 4cm/s. Find the rate of spread area after 7 minutes. [6 marks] Melaka airline policy states that all baggage must be in a bOx-shaped with the sum of length, width, and height not exceeding 480 inches. Find the dimensions of the box with square base and maximum volume. [10 marks]