Question

Daca M= {x ∈ N/x ≤ 69}, card M=?

Answer 1

Card M=70 ,pentru ca se iau 69 de numere si 0

Answer 2

$M = \Big\{x\in \mathbb_{N}\Big| x\leq 69\Big\} \\ \\ x\leq 69 \Rightarrow x \in (-\infty, 69], dar, x\in \mathbb_{N} \Rightarrow x\in\Big\{0,1,2,3,...,69\Big\} \Rightarrow \\ \\ \Rightarrow M = \Big\{0,1,2,3,...,69\Big\} \Rightarrow \boxed{ card M = 70}$