JAMB 2018 Mathematics · Question 58
Evaluate ∫ dx
Options
- A.1.47
- B.2.67
- C.3.23
- D.3.47
Answer: D. 3.47
Explanation written with AI and checked against the answer key
Analyze the question: We need the definite integral of 5/x from x = 1 to x = 2. Concept: The integral of 1/x is ln|x|. A constant multiplier can be taken outside the integral. Solution: ∫₁² (5/x) dx = 5 [ln x]₁² = 5(ln 2 − ln 1) = 5(0.6931 − 0) = 3.4657 ≈ 3.47 Check against the options: 3.47 matches option D. Answer: D. 3.47 Tip: Remember ln 1 = 0 and ln 2 ≈ 0.693. Any time you see ∫ k/x dx, think "k × ln x". Here, 5 × 0.693 ≈ 3.47 can be done quickly in your head during the exam.AI can make mistakes. Report anything that looks wrong.
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