If log base x of (9/16) equals −1/2, find x.
Aptitude
Logarithm
Difficulty: Medium
Choose an option
-
A256/81
-
B81/256
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C16/9
-
D9/16
Answer
Correct Answer: 256/81
Explanation
Given data
- logx(9/16) = −1/2
Concept / Approach
- Use the definition of logarithm: logx(A) = k implies xk = A.
- Work carefully with negative fractional exponents.
Step-by-step calculation
logx(9/16) = −1/2 ⇒ x−1/2 = 9/16x−1/2 = 1/√x, so 1/√x = 9/16√x = 16/9x = (16/9)2 = 256/81x = 256/81
Verification
x−1/2 = (256/81)−1/2 = (√(256/81))−1 = (16/9)−1 = 9/16, which matches.
Common pitfalls
- Treating −1/2 as −0.5 but then squaring the wrong quantity.
- Inverting 9/16 instead of the base power expression.
Final Answer
256/81