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 `720` (b) 120 (c) 0 (d) none of these
A. 720
B. 120
C. 0
D. None of these

Answer 1

Correct Answer - C
We know that, if A and B are two non-empty finite set containing m and n elements respectively, then the number of one-one and onto mapping from A to B is
n! if m = n
0 if m `ne` n
Given that, m = 5 and n = 6
` :. M ne n`
Number of mapping = 0