ECZ 2023 · O-Level Paper 1 — Sequences and Series
Given that 25 and 13 are the first and third terms of an arithmetic progression respectively, find the (b) formula for the nth term.
- A. 31 + 6n
- B. 31 - 6n
- C. 25 + 6n
- D. 25 - 6n
Verified working — step 1
Substitute a and d into Tn = a + (n - 1)d, then expand with care: the -6 multiplies both n and -1.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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