If log base x of (9/16) equals −1/2, find x.

Aptitude Logarithm Difficulty: Medium
Choose an option
  • A
    256/81
  • B
    81/256
  • C
    16/9
  • D
    9/16

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

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