Question

Aflati cardinalul multimii A={× € N | x divide pe 15

Answer 1

A={x∈N I x I 15}
x I 15
x∈D15
x∈{1,3,5,15}
A={1,3,5,15}
card(A)=4

Answer 2

$A=D_{15}$
$D_{15}=\{1,3,5,15\}$
$A=\{1,3,5,15\}$
$cardA=4$