Question

If the set `A` contains 5 elements and the set B contains 6 elements, then the number of one-one and onto mappings from A to B is (a)720 (b) 120 (c) 0 (d) none of these

Answer 1

As there are `5` elements in set `A` and `6` elements in set `B`,
if we try to make a one -one function from `A` to `B`, one element of `B` is not used.
So, function will not be onto.
If we try to make an onto function, then at least one of the elements of `A` should have more than one mapping to set `B`.
In this case, it will not be a one-one function.
So, we can not create a function that is both onto and one-one with the given sets.
So, option `(c)` is the correct option.