Question

Dau 50 puncte URGENT​

Answer 1

$\it |x|\leq3 \Rightarrow -3\leq x\leq3 \Rightarrow A=\{-3,\ -2,\ -1,\ 0,\ 1,\ 2\ ,3\}\\ \\ \dfrac{4}{x+1}\in\mathbb{Z} \Rightarrow x+1|4 \Rightarrow x+1\in D_4 \Rightarrow x+1\in\{\pm1,\ \pm2,\ \pm4\} \Rightarrow \\ \\ \Rightarrow x+1\in\{-4,\ -2,\ -1,\ 1,\ 2,\ 4\}|_{-1} \Rightarrow x\in\{-5,\ -3,\ -2,\ 0,\ 1,\ 3\} \Rightarrow \\ \\ \Rightarrow B=\{-5,\ -3,\ -2,\ 0,\ 1,\ 3\}\\ \\ card(A)=7,\ \ \ card(B)=6\\ \\ card(A\rm{x}B)=\it7\cdot6=42$