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WAEC Mathematics 1993 Question 6

Question 6

Progressions

The nth term of a sequence is given by (−1)n−2 2n−1. Find the sum of the second and third terms.

  1. A.−2
  2. B.1
  3. C.2
  4. D.6
  5. E.12
Show the answer and explanation

Answer: A (−2)

Explanation

n = 2: (−1)0 × 21 = 2. n = 3: (−1)1 × 22 = −4. Sum = 2 + (−4) = −2.