Question

Aflati caedinalul multimii A={ x apartine N | x divide pe 15}
( Dau coroana )

Answer 1

A={x∈N|x|15}
x|15 ⇒ x∈D15={1,3,5,15}
⇒ A={1,3,5,15}
cardA=4

Answer 2

$\it A = \{x\in\mathbb{N}\Big| \ x|15\} = \{1,\ 3,\ 5,\ 15\} \Longrightarrow card(A) =4$