[tex]\dfrac{-21}{7}=-3\in \mathbb_{Z}\quad $ $ $(A)$ \\ \\ 5,(3) \in \mathbb_{R}\quad $ (A) \\ \\ 2-\sqrt{11}\in \mathbb_{Q}\quad $ $ $(F) \\ \\ 7\sqrt7-8 \in \mathbb_{I_+}$ $ \\ \\ \sqrt{7}\ \textgreater \ \sqrt{4}\Rightarrow \sqrt{7}\ \textgreater \ 2\Big|\cdot 7 \Rightarrow 7\sqrt7\ \textgreater \ 14\Big|-8 \Rightarrow 7\sqrt7-8\ \textgreater \ 4 $ $ $(pozitiv) \\ \\ \Rightarrow 7\sqrt7-8 \in \mathbb_{I_+}\quad $(A)[/tex]
