The number of functions f : \1, 2, 3, 4\ \a, b, c\, which are not onto, is :
- 48
- 45
- 51
- 35
Answer
(2) 45
Solution
Total number of functions =34=81
Onto functions (inclusion–exclusion): 34-3C1 24+3C2 14=81-48+3=36
Functions which are not onto =81-36=45
Answer: (2)