ECZ 2020 · O-Level Paper 2 · Question 5 — Sequences and Series

Question from ECZ 2020 · O-Level Paper 2 · Question 5

(a) Simplify 2 - 18p23p + 1.[2]

Verified working — step 1

2 - 18p2 = 2(1 - 9p2) = 2(1 - 3p)(1 + 3p).

(b) The first three terms of a geometric progression are: m - 2, m + 1 and m + 7. Find

(b(i)) the value of m,[3]

Verified working — step 1

Consecutive GP terms share a ratio: m + 1m - 2 = m + 7m + 1.

(b(ii)) the common ratio,[2]

Verified working — step 1

With m = …

(b(iii)) the sum of the first 6 terms.[2]

Verified working — step 1

Sn = arn - 1r - 1 with a = 3, r = 2:

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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