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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 ______.
Options
720
120
0
none of these
Solution
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 0.
Explanation:
Set A contains 5 elements and the set B contains 6 elements.
For one-one function each element in set B is assigned to only one element in set A.
Thus only '5' elements in set B are assigned to '5' elements of set 'A'
Thus range of function does not contain all '6' elements of set 'B'.
Thus if function is one-one it cannot be onto
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