11) A company training program determines that, on average, a new employee can do P(x) pieces of work per day after s days of on-the-job training, where P(x) = 90 + 60x x + 5 . Find lim x5 P(x).

12) Suppose that the value V of a certain product decreases, or depreciates, with time t, in months, where V(t) = 100 - 60t2/ (t + 2) 2 . Find V (t) lim t .

13)Use the definition f'(x) = lim h0 f(x + h) - f(x) h to find the derivative at x. 13) f(x) = 4x + 3x3