4 votes 4 votes Let $n(A)$ denotes the number of elements in set $A$. If $n (A) = p$ and $n(B) = q$, then how many ordered pairs $(a, b)$ are there with $a∈A$ and $b∈B$? (a) $p^2$ (b) $p\times q$ (c) $p+q$ (d) $2^{pq}$ Set Theory & Algebra set-theory&algebra set-theory + – Prasanna asked Nov 27, 2015 • retagged Dec 19, 2015 by Arjun Prasanna 2.4k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 4 votes 4 votes Take any two sets and try to make ordered pair..A ={1,2,3,4,5....n}B = {1,2,3,4,....n}{(a,b)} = {(1,1) (1,2) (1,3)....(1,n) (2,1) (2,2)....(2,n)........(n,n)}|{(a,b)}| = p*q Digvijay Pandey answered Nov 27, 2015 • selected Nov 27, 2015 by Prasanna Digvijay Pandey comment Share Follow See all 0 reply Please log in or register to add a comment.
4 votes 4 votes No of ordered pairs will be pq ( every element of A can be combine with every element of q) Pooja Palod answered Nov 27, 2015 Pooja Palod comment Share Follow See all 2 Comments See all 2 2 Comments reply Prasanna commented Nov 27, 2015 reply Follow Share Need a little bit explanation Pls. 0 votes 0 votes amarVashishth commented Nov 27, 2015 reply Follow Share fix an element from $p$ set and make its ordered pair with every other element of $q$. Doing this for all $p$ elements will give $p \times q$ ordered pairs. 4 votes 4 votes Please log in or register to add a comment.