passwella.
Menu

WAEC Mathematics 1993 Question 26

Question 26

Progressions

State the fifth and seventh terms of the sequence −2, −3, −4½ …………

  1. A.−81/8, −729/32
  2. B.8/81, 72/39
  3. C.27/729, −718/39
  4. D.−27/16, −79/81
  5. E.−21/8, 32/618
Show the answer and explanation

Answer: A (−81/8, −729/32)

Explanation

This is a G.P. with a = −2 and r = 3/2. T5 = −2 × (3/2)4 = −81/8 and T7 = −2 × (3/2)6 = −729/32.