If $\log_{10000} x = -\frac{1}{4}$, then $x$ is equal to
Aptitude
Logarithm
Difficulty: Easy
Choose an option
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A$\frac{1}{10}$
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B$\frac{1}{100}$
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C$\frac{1}{1000}$
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D$\frac{1}{10000}$
Answer
Correct Answer: $\frac{1}{10}$
Explanation
Concept & Formula
The fundamental definition of a logarithm connects it directly to exponents. If a logarithm is written as $\log_a b = c$, it can be converted to its exponential form:
$$b = a^c$$
Step-by-Step Solution
* **Given:** $\log_{10000} x = -\frac{1}{4}$
* **Conversion:** Convert the logarithmic equation into its equivalent exponential form.
$$x = (10000)^{-\frac{1}{4}}$$
* **Prime Factorization:** Express the base $10000$ as a power of $10$. We know that $10000 = 10^4$.
$$x = (10^4)^{-\frac{1}{4}}$$
* **Exponent Rules:** Apply the power of a power property, which states $(a^m)^n = a^{mn}$.
$$x = 10^{4 \times -\frac{1}{4}}$$
* **Simplification:** The $4$ in the numerator and denominator cancel out.
$$x = 10^{-1}$$
* **Final Value:** Use the negative exponent rule $a^{-n} = \frac{1}{a^n}$.
$$x = \frac{1}{10}$$
Exam Strategy & Shortcut
When dealing with large powers of $10$ and fractional exponents, always rewrite the large base as a power of $10$ first. Recognizing $10000$ as $10^4$ mentally allows you to immediately cancel the $4$ in the denominator of the exponent $-\frac{1}{4}$, jumping straight to $10^{-1}$ and skipping unnecessary written steps.
Common Pitfall
A frequent mistake is interpreting a negative exponent as making the entire number negative (e.g., thinking the answer is $-10$ or $-\frac{1}{10000}$). Remember that negative exponents dictate reciprocals, not negative values.
Final Answer
**Therefore, the correct answer is $\frac{1}{10}$.**