How many functions can be defined from a set A containing 5 elements to a set B having 3 elements. How many these are surjective functions.
Image of each element of A can be taken in 3 ways.
∴ Number of functions from A to B = 35 = 243.
Number of into functions from A to B = 25 + 25 + 25 – 3 = 93.
∴ Number of onto functions = 150.
