ECZ 2017 · GCE Paper 2 · Question 2 — Sequences and Series
Question from ECZ 2017 · GCE Paper 2 · Question 2
(a) Simplify m2 - 1m2 - m.[2]
Verified working — step 1
Factorise top and bottom.(b) The first three terms of a geometric progression are 6 + n, 10 + n and 15 + n. Find
(b(i)) the value of n,[2]
Verified working — step 1
In a GP consecutive ratios are equal: 10 + n6 + n = 15 + n10 + n.(b(ii)) the common ratio,[2]
Verified working — step 1
Substitute n = 10: the terms become 16, 20 and 25.(b(iii)) the sum of the first 6 terms of this sequence.[3]
Verified working — step 1
Sn = arn - 1r - 1 with a = 16, r = 54, n = 6.The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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