Comprehension

Consider the following for the two (02) items that follow:
The function f(x) satisfies  \(f(x), f \left( \frac{x}{y} \right) = \frac{f(x)}{f(y)}.\)  ​for all positive real values of x and y, and f(2) = 3

What is f(1)f(4) equal to?

This question was previously asked in
NDA-I (Mathematics) Official Paper (Held On: 13 Apr, 2025)
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  1. 4
  2. 8
  3. 9
  4. 18

Answer (Detailed Solution Below)

Option 3 : 9
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Detailed Solution

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Calculation:

Given,

The function satisfies the functional equation:

\( f\left(\frac{x}{y}\right) = \frac{f(x)}{f(y)} \)

Also, we are given that:

\( f(2) = 3 \)

We use the functional equation to calculate f(4) . Substituting x = 4 and y = 2 , we get:

\( \frac{f(4)}{f(2)} = f(2) \)

\( \frac{f(4)}{3} = 3 \quad \Rightarrow f(4) = 3 \times 3 = 9 \)

\( \frac{f(2)}{f(2)} = f(1) \quad \Rightarrow f(1) = 1 \)

\( f(1) \times f(4) = 1 \times 9 = 9 \)

Hence, the correct answer is Option 3.

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