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JAMB Mathematics 2002 Question 19

Question 19

Progressions

If the 9th term of an A.P. is five times the 5th term, find the relationship between a and d.

  1. A.2a + d = 0
  2. B.3a + 5d = 0
  3. C.a + 3d = 0
  4. D.a + 2d = 0
Show the answer and explanation

Answer: C (a + 3d = 0)

Explanation

a + 8d = 5(a + 4d) gives a + 8d = 5a + 20d, so 4a + 12d = 0, i.e. a + 3d = 0.