ECZ 2018 · GCE Paper 1 — Sequences and Series
The first three terms in an arithmetic progression are 5, 7 and 9. Find the sum of the first 12 terms.
- A. 192
- B. 27
- C. 384
- D. 96
Verified working — step 1
"Sum of the first 12 terms" calls for the sum formula Sn = n2(2a + (n - 1)d) - not the 12th term.The full step-by-step working and final answer, plus the video lesson for this topic, 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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