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JAMB Mathematics 2009 Question 37

Question 37

Differentiation

If s = (2 + 3t)(5t − 4), find ds/dt when t = 4/5 secs.

  1. A.0 units per sec.
  2. B.15 units per sec.
  3. C.22 units per sec.
  4. D.26 units per sec.
Show the answer and explanation

Answer: C (22 units per sec.)

Explanation

s = 15t2 − 2t − 8, so ds/dt = 30t − 2 = 24 − 2 = 22 at t = 4/5.