SOF International Mathematics Olympiad (IMO)
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Set D
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2025
.
Sample
Find the 22th term of the AP: -3, -8, -13, ...
Explanation
Explanation
The nth term of an AP is aₙ = a + (n-1)d, where a = -3 (first term) and d = -5 (common difference). So the 22th term = -3 + (22-1)(-5) = -3 + -105 = -108.
PRO TIP
Re-check your working by substituting the answer back into the original question.