The value of $(\sqrt{8})^{\frac{1}{3}}$ is
Aptitude
Surds and Indices
Difficulty: Medium
Choose an option
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A2
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B4
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C$\sqrt{2}$
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D8
Answer
Correct Answer: $\sqrt{2}$
Explanation
### Concept & Formula
This question requires converting a radical (square root) into a fractional exponent, and then applying the power of a power rule.
$$ \sqrt[n]{x} = x^{\frac{1}{n}} $$
$$ (x^a)^b = x^{ab} $$
### Step-by-Step Solution
* **Given:**
The expression to evaluate is $(\sqrt{8})^{\frac{1}{3}}$.
* **Calculation:**
1. Convert the square root of $8$ into a fractional exponent:
$\sqrt{8} = 8^{\frac{1}{2}}$
2. Substitute this back into the original expression:
$(8^{\frac{1}{2}})^{\frac{1}{3}}$
3. Apply the power of a power rule by multiplying the fractions:
$8^{(\frac{1}{2} \times \frac{1}{3})} = 8^{\frac{1}{6}}$
4. Convert the base $8$ into a prime base to simplify further. We know $8 = 2^3$.
$(2^3)^{\frac{1}{6}}$
5. Multiply the exponents again:
$2^{(3 \times \frac{1}{6})} = 2^{\frac{3}{6}}$
6. Simplify the fraction in the exponent:
$2^{\frac{1}{2}}$
7. Convert the fractional exponent back to a radical for the final answer:
$\sqrt{2}$
### Exam Strategy & Shortcut
Reverse the order of operations for speed. The power $\frac{1}{3}$ is a cube root. The expression is effectively the cube root of the square root of $8$. Because $8$ is a perfect cube ($2^3$), handle the cube root first! The cube root of $8$ is $2$. You are left with just the square root over that $2$, resulting instantly in $\sqrt{2}$.
### Common Pitfall
Students often struggle with nested radicals and fractional powers. A common mistake is to multiply the base by the exponent (e.g., $8 \times \frac{1}{3}$) instead of recognizing it as a root. Always convert roots to fractions if you are unsure how to proceed.
### Final Answer
**Therefore, the correct answer is $\sqrt{2}$.**