English

Let f: [0, 1] → [0, 1] be defined by f(x) = ,ifis rational,ifis irrational{x, if x is rational1-x, if x is irrational. Then (f o f) x is ______.

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Question

Let f: [0, 1] → [0, 1] be defined by f(x) = `{{:(x",",  "if"  x  "is rational"),(1 - x",",  "if"  x  "is irrational"):}`. Then (f o f) x is ______.

Options

  • Constant

  • 1 + x

  • x

  • None of these

MCQ
Fill in the Blanks
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Solution

Let f: [0, 1] → [0, 1] be defined by f(x) = `{{:(x",",  "if"  x  "is rational"),(1 - x",",  "if"  x  "is irrational"):}`. Then (f o f) x is x.

Explanation:

Given that, f: [0, 1] → [0, 1] be defined by

f(f(x)) = `{{:(f(x)",",  "if"  f(x)  "is rational"),(1 - f(x)",",  "if"  f(x)  "is  irrational"):}`

=  `{{:(x",",  "if"  x  "is rational"),(1 - (1 - x)",",  "if"  1 - x  "is  irrational"):}`

= `{{:(x",",  "if"  x  "is rational"),(x",",  "if"  x  "is irrational"):}`

∴ (fof)x = f(f(x)) = x

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Chapter 1: Relations And Functions - Exercise [Page 15]

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NCERT Exemplar Mathematics Exemplar [English] Class 12
Chapter 1 Relations And Functions
Exercise | Q 43 | Page 15

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