Negative and fractional exponents: Simplify (x^(2/3))^(−3/4) and express it with positive exponents if possible.
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A1/x
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B1/√x
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C1/x^2
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D1/x^(−2)
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E√x
Answer
Correct Answer: 1/√x
Explanation
Introduction / Context:This checks the power-of-a-power rule and handling negative exponents. We convert the nested exponent to a single exponent on x, then rewrite with a positive exponent as a reciprocal if needed.
Given Data / Assumptions:
- Expression: (x^(2/3))^(−3/4)
- x > 0 for real radical interpretation.
Concept / Approach:Use (a^m)^n = a^(mn). Multiply exponents 2/3 and −3/4 to get a single exponent. A negative exponent −k means 1/x^k. Convert x^(−1/2) to 1/√x.
Step-by-Step Solution:(x^(2/3))^(−3/4) = x^((2/3)*(−3/4)) = x^(−6/12) = x^(−1/2)x^(−1/2) = 1 / x^(1/2) = 1/√x
Verification / Alternative check:Test x = 16: LHS = (16^(2/3))^(−3/4). 16^(2/3) = (2^4)^(2/3) = 2^(8/3). Raising to −3/4 yields 2^(−2) = 1/4. RHS 1/√16 = 1/4—matches.
Why Other Options Are Wrong:1/x and 1/x^2 correspond to exponents −1 and −2; 1/x^(−2) simplifies to x^2; √x is the reciprocal of the answer.
Common Pitfalls:Adding instead of multiplying exponents inside a power-of-a-power; mishandling negative signs.
Final Answer:1/√x