Simplify an expression with cube roots and negative powers: Compute ∛(x^6) ÷ ∛(x^12) × x^(−3) × ∛(x^9).

Difficulty: Easy

Correct Answer: 1/x^2

Explanation:


Introduction / Context:
This problem combines cube roots with integer and negative exponents. Converting all radicals to fractional exponents allows straightforward combination via exponent addition and subtraction rules.

Given Data / Assumptions:

  • Expression: x^(6/3) ÷ x^(12/3) × x^(−3) × x^(9/3).
  • Assume x ≠ 0 to avoid division by zero.


Concept / Approach:
Use ∛(x^k) = x^(k/3). Then combine exponents linearly: when multiplying, add exponents; when dividing, subtract exponents. Keep track of the signs carefully, especially for the negative power term x^(−3).

Step-by-Step Solution:

∛(x^6) = x^(6/3) = x^2.∛(x^12) = x^(12/3) = x^4.∛(x^9) = x^(9/3) = x^3.Combine: x^2 / x^4 × x^(−3) × x^3 = x^(2 − 4 − 3 + 3) = x^(−2) = 1/x^2.


Verification / Alternative check:
Pick x = 2: ∛(64)/∛(4096) × 2^(−3) × ∛(512) = 4/16 × 1/8 × 8 = (1/4) × (1/8) × 8 = 1/4 = 1/2^2, confirming 1/x^2.


Why Other Options Are Wrong:

  • 1/x, x, 1: Each misses at least one exponent step or cancels incorrectly.


Common Pitfalls:
Forgetting that dividing by x^4 reduces exponent by 4, or cancelling x^(−3) incorrectly with x^3.


Final Answer:

1/x^2

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