A firm has the marginal-demand function D' (x) = -3000r 41-r' where D (x) is the number of units sold at x dollars per unit. Find the demand function given that D = 16, 000 when * =$5 per unit. O Not listed here 3000 \\/41 - x2 + 4000 O 3000 /41 - x2 + 28000 O 3000 (41-2-2 + 15815.50Shylls Inc finds that the marginal profit, in dollars per board, from the sale of x digital control boards is given by P' (x) = 2.6201 A customer orders 1200 digital control boards and later increases the order to 1500. Find the extra profit resulting from the increase in order size. $5763.42 $13130.25 O $1603.42 O Not listed here