Can you please help me with this calc 3 problem set?

The daily cost (in dollars) of producing LG ultra high definition televisions is given by C(x) = 4x3 - 20x2 + 90x + 400 where x denotes the number of thousands of televisions produced in a day. Using the Marginal Average Cost function, C'(x), approximate the marginal average cost when 2000 televisions have been produced. -104 -109 0 -99 O -89 0 -94 Viewing Saved Work Revert to Last Response 8 V MY NOTE A company is increasing production of math-brain protein bars at a rate of 500 cases per day. All cases produced can be sold. The daily demand function is given by p(x) = 80 - - X 200' where x is the number of cases produced and sold, and p is in dollars. Find the rate of change of the revenue with respect to the time in days when the daily production is 600 cases. 37,200 dollars per day 37,500 dollars per day 37,800 dollars per day 37,000 dollars per day 36,600 dollars per day Viewing Saved Work Revert to Last Response 9. V MY NOTE A billboard designer has decided that a sign should have 4-ft margins at the top and bottom and 1-ft margins on the left and right sides. Furthermore, the billboard should have a total area of 400 ft (including the margins). If x denotes the width (in feet) of the billboard, find the value of x that maximizes the area of the printed region of the billboard. 10 O 40 O 30 O 50