Cartesian product Help

Question

Let A={x e N | 2x-7<0} and .b={x e N | x^2<4}

 

a. Describe the Cartesian product A x B by listing its elements 

 

b. Describe the Cartesian product B x A by listing its elements. 

Answer 1

 the Natural numbers are the counting numbers which are 1,2,3,4,5....

So the natural numbers that satisfy A come from solving 2x-7<0.....2x<7.......x<3.5

That makes set A ={1,2,3}

 

For set B x²<4 has only 1 natural number that solves it, so set B = {1}

 

So A X B is the set of ordered pairs where the first number comes from set A and the second number comes from set B.

So A x B = {(1,1) , (2,1) , (3,1)} and B x A = (1,1) (1,2) (1,3)}

 

Hope this helped.