WAEC 2022 Mathematics · Question 44

Find the 17term of the Arithmetic Progression (A.P):-6,-1,4

Options

A.-91
B.-86
C.74
D.79

Answer: C. 74

Explanation written with AI and checked against the answer key

Analyze the question: We have an A.P. with first term a = -6, and we need the 17th term. Concept: The nth term of an A.P. is Tₙ = a + (n − 1)d Find the common difference: d = -1 − (-6) = 5 Check: 4 − (-1) = 5 ✓ Solve: T₁₇ = -6 + (17 − 1)(5) T₁₇ = -6 + 16 × 5 T₁₇ = -6 + 80 T₁₇ = 74 Answer: The 17th term is 74, which is option C. Tip: Always subtract (n − 1), not n, when using the formula. The first term already counts as term 1, so you only add the common difference 16 times to reach term 17. Also be careful with the signs: the negative first term is why options A and B (the negative ones) are traps for students who slip on the sign of d or of a.

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