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Let f: R → R be defined by f(x) = ,,,{2x,x>3x2,1<x≤33x,x≤1. Then f(–1) + f(2) + f(4) is ______. - Mathematics

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Question

Let f: R → R be defined by f(x) = `{{:(2x",", x > 3),(x^2",", 1 < x ≤ 3),(3x",", x ≤ 1):}`. Then f(–1) + f(2) + f(4) is ______.

Options

  • 9

  • 14

  • 5

  • None of these

MCQ
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Solution

Let f: R → R be defined by f(x) = `{{:(2x",", x > 3),(x^2",", 1 < x ≤ 3),(3x",", x ≤ 1):}`. Then f(–1) + f(2) + f(4) is 9.

Explanation:

Given that, f(x) = `{{:(2x",", x > 3),(x^2",", 1 < x ≤ 3),(3x",", x ≤ 1):}`

f(–1) = 3(–1) = –3  .....(Using f(x) = 3x)

f(2)= 22 = 4  ......(Using f(x) = x2)

f(4) = 2(4) = 8  ......(Using f(x) = 2x)

∴ f(–1) + f(2) + f(4) = 3 + 4 + 8 = 9

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Chapter 1: Relations And Functions - Exercise [Page 16]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 1 Relations And Functions
Exercise | Q 46 | Page 16

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