ECZ 2019 · GCE Paper 1 — Sequences and Series
For the sequence −10, −7, −4, −1, …, find the sum of the first 20 terms.
- A. 370
- B. 740
- C. 570
- D. 185
Verified working — step 1
Use the sum formula Sn = n2(2a + (n - 1)d) - and finish the whole bracket before touching the n2.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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