Combine like bases (indices law): Evaluate a^5 × a^7 and express the result as a single power of a.

Aptitude Surds and Indices Difficulty: Easy
Choose an option
  • A
    a^35
  • B
    a^2
  • C
    a^12
  • D
    a^(5/7)
  • E
    a^10

Answer

Correct Answer: a^12

Explanation

Introduction / Context:This is a direct application of the index law a^m * a^n = a^(m+n). We combine exponents with the same base by simple addition.

Given Data / Assumptions:

  • a^5 × a^7
  • a ≠ 0 (usual nonzero base assumption)

Concept / Approach:When multiplying powers with the same base, add exponents: m + n. No further simplification is needed beyond adding 5 and 7.

Step-by-Step Solution:a^5 × a^7 = a^(5 + 7) = a^12

Verification / Alternative check:For a = 2: 2^5 × 2^7 = 32 × 128 = 4096 = 2^12, as expected.

Why Other Options Are Wrong:a^35 multiplies exponents incorrectly; a^2 subtracts instead of adds; a^(5/7) is unrelated; a^10 is adding wrongly.

Common Pitfalls:Multiplying exponents (5*7) instead of adding—only (a^m)^n multiplies exponents.

Final Answer:a^12

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