# If A={a,1,-1,x} and B is another set such that the number of relation from A to B are 4096, then find the number of elements in set B???

We know that,total number of subsets of A cross B is equal to total number of relation from A to B. Number of relation from A to B=total no. of subsets of A cross B=2 ^4*b. Now according to question. 2^4*b=4096. 2^4*b=2^12. Bases are same so. 4*b=12. b=3 and required no. of elements of set B is 3