_ , A company estimates that it wiil sell N(x) units of a product after spending $x thousand on advertising, as given by 7\" NO!) = 0.25x4 + 22x3 - 472.53? + 34,000. where 21 s x s 45. When is the rate of change of sales increasing and when is it decreasing? What is the point at diminishing returns and the maximum rate of change of sales? Graph N and N' on the same coordinate system. a- E The rate of change of sales is increasing on m