0 votes 0 votes Shadan Karim asked Jan 5, 2019 Shadan Karim 201 views answer comment Share Follow See all 3 Comments See all 3 3 Comments reply Shubhgupta commented Jan 5, 2019 reply Follow Share 5!= 120? 0 votes 0 votes Shadan Karim commented Jan 5, 2019 reply Follow Share How 5! ?? 0 votes 0 votes Shubhgupta commented Jan 5, 2019 reply Follow Share those functions which are having inverse are called invertible function. inverse function- $a->f(x)->b->f^{-1}(x)->a$ so in question A and B are having 5 elements. So according to definition 1(from A) is having 5 choices(1,2,3,4,5 from B), 2 is 4 choices .....like that go on. so total functions- 5!= 120 1 votes 1 votes Please log in or register to add a comment.