Question

If n(P) = 3 , n(a) = 1, then find the number of relations from PxQ to QxP.​

Answer 1

This is refered as Descartes Multiplication(Product)

I think wikipedia page says a lot but i will give it a try, Cartesian product’s idea is to take set A as a column and set B as a row in which each square has coresponding (x, y) value.

It’s worth to NOTE that A ×B doesn’t always equal to B×A

Why? Well let’s use P and Q ‘s elements.

We will have 2 idenependent Set:

P x Q = {(1, 2), (1, 3), … ,(3, 4)}

Q x P ={ (2, 1), (2, 2), …, (4, 3)}

They will clearly give you two different geometrical object on xoy cordinate axis.

Try plotting it.