Question

A={x€N|X<100 si x se divide cu 11}

Answer 1

A={11;22;33;44;55;66;77;88;99};

Answer 2

$A=\Big\{\text{x}\in\mathbb_{N} \Big| \text{x}\ \textless \ 100 si \text{x} \vdots 11}\Big\} \\ \\ \\ \Rightarrow \left\{ \begin{array}{c} \text{x} \in M_{11} \\\text{x} \ \textless \ 100 \end{array} \right \Rightarrow\left\{ \begin{array}{c} \text{x} \in \Big\{11,22,33,44,...,\infty\Big\} \\\text{x} \ \textless \ 100\quad \quad \quad \quad\quad \quad \quad \end{array} \right |\Rightarrow$

$\Rightarrow \text{x} \in \Big\{11,22,33,44,55,66,77,88,99\Big\},\quad dar, x \in \mathbb_{N} \Rightarrow \\ \\ \\ \Rightarrow \boxed{A = \Big\{11,22,33,44,55,66,77,88,99\Big\}}$