Question
Question: If A = {1, 2, 3,4} and f : A → A, the total number of invertible functions, ‘f’, such that f(2) ≠ 2,...
If A = {1, 2, 3,4} and f : A → A, the total number of invertible functions, ‘f’, such that f(2) ≠ 2, f(4) ≠ 4, f(1) = 1 is equal to
A
1
B
2
C
3
D
None of these
Answer
3
Explanation
Solution
If f(2) = 3 then f(4) = 2, f(1) = 1, f(3) = 4. On the other hand if f(2) = 4 then f(4) = 3 or 2. Thus there are three invertible functions.