$7\mathrm{.}1$ Exercises

In Exercises $1$ through $8,$ each relation $R$ is defined on the set A$.$ In each case determine if $R$ is a tree and, if it is$,$ find the root.

$1.$

$A=\{a,b,c,d,e\}$

$R=\{(a,d),(b,c),(c,a),(d,e)\}$

$A=\{a,b,c,d,e\}$

$R=\{(a,b),(b,e),(c,d),(d,b),(c,a)\}$