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Let f: R – {35} → R be defined by f(x) = 3x+25x-3. Then ______.

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Question

Let f: R – `{3/5}` → R be defined by f(x) = `(3x + 2)/(5x - 3)`. Then ______.

Options

  • f–1(x) = f(x)

  • f–1(x) = – f(x)

  • (f o f)x = – x

  • f–1(x) = `1/19` f(x)

MCQ
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Solution

Let f: R – `{3/5}` → R be defined by f(x) = `(3x + 2)/(5x - 3)`. Then f–1(x) = f(x).

Explanation:

We have f(x) = `(3x + 2)/(5x - 3)` = y ......(Let)

⇒ 3x + 2 = 5xy – 3y

⇒ x(3 – 5y) = –3y – 2

⇒ x = `(3y + 2)/(5y - 3)`

⇒ f–1(x) = `(3x + 2)/(5x - 3)`

∴ f–1(x) = f(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 42 | Page 15

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