Evaluate a power-of-a-power ratio: Simplify the expression [(12)^(−2)]^2 ÷ [(12)^2]^(−2) and give the exact value.

Difficulty: Easy

Correct Answer: 1

Explanation:


Introduction / Context:
This tests exponent laws, specifically (a^m)^n = a^(m n), and how negative exponents invert the base. Carefully apply the rules to both numerator and denominator before simplifying the ratio of equal powers.


Given Data / Assumptions:

  • Expression: [(12)^(−2)]^2 ÷ [(12)^2]^(−2).
  • Use standard laws of indices.


Concept / Approach:
Compute the power of a power for both parts, reduce each to a single power of 12, then divide. Identical powers in numerator and denominator will cancel to 1.


Step-by-Step Solution:

Numerator: [(12)^(−2)]^2 = 12^(−4).Denominator: [(12)^2]^(−2) = 12^(2 * −2) = 12^(−4).Ratio = 12^(−4) / 12^(−4) = 12^(−4 − (−4)) = 12^0 = 1.


Verification / Alternative check:
Assign 12^(−4) = 1/12^4 for both; clearly their quotient is 1.


Why Other Options Are Wrong:

  • 12, 4.8, 12/144, 1/12: Result from arithmetic slips or misapplying negative exponents.


Common Pitfalls:
Forgetting that raising to a negative exponent inverts, and that dividing equal powers subtracts exponents.


Final Answer:
1

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