JAMB 2018 Mathematics · Question 38
Simplify
Options
- A.25
- B.1
- C.
- D.
Answer: A. 25
Explanation written with AI and checked against the answer key
Analyze the question: We have to simplify a fraction in which both the numerator and denominator involve division of powers with the same base. The key tool is the law of indices: a^m ÷ a^n = a^(m−n).
Concept:
- a^m ÷ a^n = a^(m−n)
- 25 = 5², so 25^k = 5^(2k)
- (1/5)^k = 5^(−k)
Step 1: Numerator
25^(2/3) ÷ 25^(1/6) = 25^(2/3 − 1/6) = 25^(4/6 − 1/6) = 25^(3/6) = 25^(1/2) = 5
Step 2: Denominator
(1/5)^(7/6) ÷ (1/5)^(1/6) = (1/5)^(7/6 − 1/6) = (1/5)^(6/6) = (1/5)^1 = 1/5
Step 3: Divide
5 ÷ (1/5) = 5 × 5 = 25
Answer: The result is 25, which is option A.
Tip: When the bases are the same and you see division, subtract the powers first, because it keeps the fractions simple. Also, dividing by a fraction means multiplying by its reciprocal, so 5 ÷ 1/5 = 5 × 5.
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