## Discrete Mathematics with Applications 4th Edition

a. $S\times T=\{(2,1), (2,3), (2,5), (4,1), (4,3), (4,5), (6,1), (6,3), (6,5)\}$. There are 9 elements in this set. b. $T\times S=\{(1,2), (1,4), (1,6), (3,2), (3,4), (3,6), (5,2), (5,4), (5,6)\}$. There are 9 elements in this set. c. $S\times S=\{(2,2), (2,4), (2,6), (4,2), (4,4), (4,6), (6,2), (6,4), (6,6)\}$. There are 9 elements in this set. d. $T\times T=\{(1,1), (1,3), (1,5), (3,1), (3,3), (3,5), (5,1), (5,3), (5,5)\}$. There are 9 elements in this set.
If there are $x$ elements in $A$ and $y$ elements in $B$, then there are $x\times y$ elements in $A\times B$.