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WAEC Further Mathematics 2022 Question 17

Question 17

Sequences and Series

If Un = kn2 + pn, U1 = −1, U5 = 15, find the values of k and p.

  1. A.k = −1, p = 2
  2. B.k = −1, p = −2
  3. C.k = 1, p = −2
  4. D.k = 1, p = 2
Show the answer and explanation

Answer: C (k = 1, p = −2)

Explanation

k + p = −1 and 25k + 5p = 15 (so 5k + p = 3). Subtracting: 4k = 4, k = 1 and p = −2.