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JEE Main 20264 AprilMorning Shift
Exam
JEE Main
Year
2026
Date
4 April
Shift
Morning Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2026 · 4 April · Morning Shift · Mathematics · Functions

The number of functions f: \ 1, 2, 3, 4\ arrow \ a, b, c\ , which...

The number of functions f:{1,2,3,4}→{a,b,c}f: \{1, 2, 3, 4\} \rightarrow \{a, b, c\}, which are not onto, is:

Options

  1. A4848
  2. B4545
  3. C5151
  4. D3535

Correct answer

B. 4545

Step-by-step solution

Total number of functions from a set of 44 elements to a set of 33 elements is 34=813^4 = 81.

The number of onto functions is given by the inclusion-exclusion principle:

34−3C124+3C2143^4 - ^{3}C_{1} 2^4 + ^{3}C_{2} 1^4

=81−3×16+3×1= 81 - 3 \times 16 + 3 \times 1

=81−48+3=36= 81 - 48 + 3 = 36

The number of functions which are not onto is the total number of functions minus the number of onto functions:

81−36=4581 - 36 = 45

Answer: 4545
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