ECZ 2020 · GCE Paper 2 · Question 2 — Sequences and Series
The sum of n terms of a geometric progression (G.P.) is given by Sn = 10 - 102^n.
(a) Simplify y + 1y^2 - 1.[2]
Verified working — step 1
Factorise the denominator: y2 - 1 = (y-1)(y+1).(b(i)) Find the sum of the first 4 terms of this G.P.[2]
Verified working — step 1
Sn = 10 - 102^n, put n = 4:(b(ii)) Find the first term.[2]
Verified working — step 1
First term = S1 (sum of first 1 term):(b(iii)) Find the first 4 terms.[3]
Verified working — step 1
Use Tn = Sn - S(n-1).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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