ECZ 2021 · O-Level Paper 2 · Question 3 — Sequences and Series

Question from ECZ 2021 · O-Level Paper 2 · Question 3

(a) The second and the fifth terms of a geometric progression are 16 and 2 respectively. Find

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

Verified working — step 1

Divide the two given terms to isolate r:

(a(ii)) the 12th term,[2]

Verified working — step 1

Tn = a rn-1 with a = 32 and r = …

(a(iii)) the sum of the first 10 terms.[2]

Verified working — step 1

Sn = a1 - rn1 - r with a = 32, r = 12:

(b) Express 51 - x - 3x - 2 as a single fraction in its lowest terms.[3]

Verified working — step 1

Common denominator (1 - x)(x - 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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