Plz solved this que.quickly

Plz solved this que.quickly 14. f: A + B such that f(x) = is onto, then the set B is

Set A belongs to the values of x.
Now we have to decide what values x can take !
^7-xP_x-3 =    (7-x)!   
                  (10-2x)!
x should be : 1. greater than or equal to 3
                      2. less than or equal to 7
                      3. less than or equal to 5
From (1),(2),(3) : x can take values from 3 to 5.
Accordingly we will get 1,2,3 as values of f(x).
B set belongs to these values of f(x) .
Therefore ans is option (3) .


HOPE THIS HELPS !!! ;)