Demand Function for Desk Lamps The demand function for the Luminar desk lamp is given by p = f(x) = 0.1x2 0.8x + 40 where x is the quantity demanded in thousands and p is the unit price in dollars. (a) Find f'(x). f'(x) = 0.2x 0.8 / (b) What is the rate of change of the unit price (in dollars per 1,000 lamps) when the quantity demanded is 3,000 units (X = 3)? $ 3004.2 3' per 1,000 lamps What is the unit price (in dollars) at that level of demand? $ 3004.2 X