ECZ 2017 · GCE Paper 2 · Question 2 — Sequences and Series

The first three terms of a geometric progression are 6 + n, 10 + n and 15 + n.

(a) Simplify m^2 - 1m^2 - m.[2]

Verified working — step 1

Factorise numerator and denominator:

(b(i)) Find the value of n.[2]

Verified working — step 1

For a GP, the ratio of consecutive terms is equal:

(b(ii)) Find the common ratio.[2]

Verified working — step 1

Substitute n = 10 into the terms:

(b(iii)) Find the sum of the first 6 terms of this sequence.[3]

Verified working — step 1

Use the GP sum formula:

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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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