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

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

(a(i)) The second and the fifth terms of a geometric progression are 16 and 2 respectively. Find the common ratio and first term.[3]

Verified working — step 1

ar = 16 and ar4 = 2.

(a(ii)) Find the 12th term.[2]

Verified working — step 1

T_12 = a r11 = 32 x (12)11 = 322048= …

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

Verified working — step 1

S_n = a1 - r^n1 - r

(b) Express 51 - x- 3x - 2as 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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