Answer :
Those three elements are, respectively,
[tex]1=5^0,\quad 5=5^1,\quad 125=5^3[/tex]
So, we can build the set as
[tex]X=\{5^i\ |\ i\in\{0,1,3\}\}[/tex]
Those three elements are, respectively,
[tex]1=5^0,\quad 5=5^1,\quad 125=5^3[/tex]
So, we can build the set as
[tex]X=\{5^i\ |\ i\in\{0,1,3\}\}[/tex]