Marta’s math textbook weighs Four-fifths of a pound less than 4 times the weight of the book she is reading for her language arts class. If the weight of the math textbook is 2 and one-fifth pounds, which shows the correct equation and value of x, the weight of Marta’s book for language arts? A -4 x + four-fifths = 2 and one-fifth; x = 7 over 20 of a pound B - 4 x minus four-fifths = 2 and one-fifth; x = three-fourths of a pound C -4 x + four-fifths = 2 and one-fifth; x = three-fourths of a pound D - 4 x minus four-fifths = 2 and one-fifth; x = 7 over 20 of a pound

If p(x) is the total value of the production when there are x workers in a plant, then the average productivity of the workforce at the plant is a(x) = p(x) x . (a) find a'(x). a'(x) = xp'(x) − p(x) x a'(x) = xp'(x) − p(x) x2 a'(x) = p'(x) − p(x) x a'(x) = xp'(x) − p'(x) x2 a'(x) = p'(x) − xp(x) x2 why does the company want to hire more workers if a'(x) > 0? a'(x) > 0 ⇒ a(x) is ; that is, the average productivity as the size of the workforce increases. (b) if p'(x) is greater than the average productivity, which of the following must be true? p'(x) − xp(x) > 0 p'(x) − xp(x) < 0 xp'(x) − p'(x) > 0 xp'(x) − p(x) < 0 xp'(x) − p(x) > 0