ECZ 2025 · O-Level Paper 2 · Question 3 — Sequences and Series

Question from ECZ 2025 · O-Level Paper 2 · Question 3

(a) Simplify 88r3 s2 t28p3 q3 ÷ 22r3 s2 t348p3 q3.[2]

Verified working — step 1

Dividing by a fraction means multiplying by its reciprocal:

(b) For the geometric progression 189, 63, 21, ..., find the

(b(i)) common ratio,[2]

Verified working — step 1

In a GP the ratio of consecutive terms is constant: r = T2/T1.

(b(ii)) 5th term,[2]

Verified working — step 1

The nth term of a GP is Tn = a rn-1.

(b(iii)) sum to infinity.[3]

Verified working — step 1

A sum to infinity exists because |r| = 13 < 1.

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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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