Answer to Question #288757 in Discrete Mathematics for Christy

Question

Let R br a realtion defined from the set A={1,2,3,4} to the set B={2,3,4,5}as a€A, b€B aRb <-> a+b=5

1. What are the orderd pairs in the relation R

2. Represent R with a matrix

Answer 1

1) Since $1+4=5$ then $\left( {1,4} \right) \in R$ .Similarly we get $(2,3) \in R,\,(3,2) \in R$ .

Then $R = \{ \left( {1,4} \right),\,(2,3),(3,2)\}$ .

Answer: $R = \{ \left( {1,4} \right),\,(2,3),(3,2)\}$

2) Let's build a matrix of relation.

If the elements are in a relationship, then write 1, otherwise - 0. We have: