Question

c) 5 € A, unde A = {xe Z | 11 ≤ x² < 49};​

Answer 1

$\it x\in\mathbb{Z},\ \ 11 < x^2 < 49 \Rightarrow 16\leq x^2\leq 36 \Rightarrow 4^2\leq x^2\leq6^2\\ \\ x=5 \Rightarrow 4^2\leq5^2\leq6^2\ \ \ (A)$