Question Number 81091 by arkanmath7@gmail.com last updated on 09/Feb/20
Commented by mind is power last updated on 09/Feb/20
$${what}\:{is}\:{b}\left({A}\right)? \\ $$
Commented by arkanmath7@gmail.com last updated on 09/Feb/20
$${cl}\left({A}\right)\:{closure}\:{of}\:{A} \\ $$$${b}\left({A}\right)\:{boundary}\:{of}\:{A} \\ $$$${d}\left({A}\right)\:{derive}\:{of}\:{A} \\ $$$$ \\ $$$$ \\ $$