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TS EAMCET · Maths · Functions

Let \(Q\) be the set of all rational numbers in \([0,1]\) and \(f:[0,1] \rightarrow[0,1]\) be defined by \[ f(x)=\left\{\begin{array}{r} x \text { for } x \in Q \ 1-x \text { for } x \notin Q \end{array}\right. \] Then, the set \(S=\{x \in[0,21]:(f o f)(x)\}\) is equal to

  1. A \([0,1]\)
  2. B \(-Q\)
  3. C \([0,1]-Q\)
  4. D \((0,1)\)
Verified Solution

Answer & Solution

Correct Answer

(A) \([0,1]\)

Step-by-step Solution

Detailed explanation

Given, \(f(x)=\left\{\begin{array}{cc}x & \text { for } x \in Q \\ 1-x & \text { for } x \notin Q\end{array}\right.\) is defined for \[ f:[0,1] \rightarrow[0,1] \] If \(x\) is rational, then \[ \begin{array}{rlrl} f(x) & =x \\ \therefore \quad & f(f(x)) & =f(x)=x \end{array} \]…