Let \(A = \{1, 2, 3\}\). The number of functions from A to A that are not one-one is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 21
Each of the 3 elements has 3 possible images, so the number of all functions from A to A is
\(3^{3} = 27\)
The one-one functions from A to A give different images to 1, 2, 3:
\(3 \times 2 \times 1 = 6\)
So the number of functions that are not one-one is
\(27 - 6 = 21\)