Question

set a has 3 elements and set b has 4 elements.Then the number of injective mapping that can be defined from a to b is________.​

Answer 1

Answer:

To define the injective functions from set A to set B, we can map the first element of set A to any of the 4 elements of set B.

Then the second element can not be mapped to the same element of set A, hence, there are 3 choices in set B for the second element of set A.

Similarly there are 2 choices in set B for the third element of set A.

Hence the total number of injective functions are 4×3×2 = 24

Answer 2

Answer:

The father of Rohit is thrice as old as Rohit.After 12 years he will be just twice his son. Find their present ages.