JAMB 2025 Mathematics · Question 6

Simplify 125−13^{−\frac{1}{3}} × 49−12^{−\frac{1}{2}} × 100^0

Options

  1. A.135\frac{1}{35}
  2. B.1350\frac{1}{350}
  3. C.350
  4. D.35

Answer: A. 135\frac{1}{35}

Explanation written with AI and checked against the answer key

Analyze the question: We need to simplify a product of three terms with negative and zero indices.

Concept:

  • A negative index means a reciprocal: a^(−n) = 1/aⁿ
  • A fractional index means a root: a^(1/n) = ⁿ√a
  • Any non-zero number to the power 0 equals 1

Solution:

  1. 125^(−1/3) = 1 / 125^(1/3) = 1 / ∛125 = 1/5, since 5³ = 125
  2. 49^(−1/2) = 1 / 49^(1/2) = 1 / √49 = 1/7
  3. 10⁰ = 1

Multiply them:

(1/5) × (1/7) × 1 = 1/35

Tip: Handle each term separately: first deal with the negative sign by taking the reciprocal, then take the root, and remember that anything to the power 0 is 1. Don't confuse 1/35 with 35, which is what you'd get if you ignored the negative signs.

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