WAEC 2024 Mathematics · Question 17
If log = 5, find the value of x
Options
- A.8
- B.16
- C.64
- D.122
Answer: D. 122
Explanation written with AI and checked against the answer key
Analyze the question The expression is most likely log₃(2x − 1) = 5, which means "log of (2x − 1) to base 3 equals 5." Concept If log_b(N) = k, then N = b^k. Solution log₃(2x − 1) = 5 2x − 1 = 3⁵ 3⁵ = 243 2x − 1 = 243 2x = 244 x = 122 Check: 2(122) − 1 = 243 and log₃(243) = 5 ✓ Answer: x = 122, which is option D. Tip: Convert a log equation to index form straight away: log_b N = k becomes N = b^k. Memorise the powers of 3: 3, 9, 27, 81, 243. Here 3⁵ = 243 is the key step.AI can make mistakes. Report anything that looks wrong.
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