ECZ 2022 · O-Level Paper 2 · Question 3 — Sequences and Series

Question from ECZ 2022 · O-Level Paper 2 · Question 3

(a) Simplify 2x + 142x2 - 98.[2]

Verified working — step 1

Factor top and bottom:

(b) Given that the third and sixth terms of a geometric progression are 34 and 332 respectively, find the

(b(i)) first term and the common ratio,[3]

Verified working — step 1

Divide the two given terms to isolate r:

(b(ii)) nth term,[2]

Verified working — step 1

nth term = a rn-1 with a = 3 and r = …

(b(iii)) sum to infinity of the progression.[2]

Verified working — step 1

|r| = 12 < 1, so a sum to infinity exists.

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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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