ECZ 2020 · GCE Paper 2 · Question 2 — Sequences and Series

Question from ECZ 2020 · GCE Paper 2 · Question 2

(a) Simplify y + 1y2 - 1.[2]

Verified working — step 1

y2 - 1 is a difference of two squares: (y - 1)(y + 1).

(b) The sum of n terms of a geometric progression (G.P) is given by 10 - 102n. Find

(b(i)) the sum of the first 4 terms of this G.P,[2]

Verified working — step 1

The sum formula is given as Sn = 10 - 102n. Put n = 4:

(b(ii)) the first term,[2]

Verified working — step 1

The first term is S1, the sum of just one term.

(b(iii)) the first 4 terms.[3]

Verified working — step 1

Each term is Tn = Sn - Sn-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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