# Math Help - Set Builder Notation? Help

1. ## Set Builder Notation? Help

A={(9,1),(8,2),(7,3),(6,4),(5,5),(4,6),(3,7),(2,8) ,(1,9)}

I am not sure how to write its set builder notation but I have tried it as follows

A = {(a,b)| ai<10 and bi>0, 0<i<10}

Any suggestion would be highly appreciated.

2. Originally Posted by mrsenim
A={(9,1),(8,2),(7,3),(6,4),(5,5),(4,6),(3,7),(2,8) ,(1,9)}
I am not sure how to write its set builder notation
$A=\{(10-k,k):k=1,2,\cdots,9\}$
That is one of several ways.