Toán TÌm x ∩, ∪ 2 tập hợp sau : a. x > 2, x < 16 b. 2x > 8, 4x > 40 06/09/2021 By Parker TÌm x ∩, ∪ 2 tập hợp sau : a. x > 2, x < 16 b. 2x > 8, 4x > 40
\(\begin{array}{l}a)\,\,x > 2 \Rightarrow A = \left\{ {x \in R|\,\,x > 2} \right\}\\x < 16 \Rightarrow B = \left\{ {x \in R|\,\,x < 16} \right\}\\ \Rightarrow A \cap B = \left\{ {x \in R|\,\,2 < x < 16} \right\}\\A \cup B = \left\{ {x \in R} \right\}.\\b)\,\,2x > 8 \Leftrightarrow x > 4 \Rightarrow A = \left\{ {x \in R|\,\,\,x > 4} \right\}\\4x > 40 \Leftrightarrow x > 10 \Rightarrow B = \left\{ {x \in R|\,\,x > 10} \right\}\\ \Rightarrow A \cap B = \left\{ {x \in R|\,\,x > 10} \right\}\\ \Rightarrow A \cup B = \left\{ {x \in R|\,\,x > 4} \right\}.\end{array}\) Trả lời
\(\begin{array}{l}
a)\,\,x > 2 \Rightarrow A = \left\{ {x \in R|\,\,x > 2} \right\}\\
x < 16 \Rightarrow B = \left\{ {x \in R|\,\,x < 16} \right\}\\
\Rightarrow A \cap B = \left\{ {x \in R|\,\,2 < x < 16} \right\}\\
A \cup B = \left\{ {x \in R} \right\}.\\
b)\,\,2x > 8 \Leftrightarrow x > 4 \Rightarrow A = \left\{ {x \in R|\,\,\,x > 4} \right\}\\
4x > 40 \Leftrightarrow x > 10 \Rightarrow B = \left\{ {x \in R|\,\,x > 10} \right\}\\
\Rightarrow A \cap B = \left\{ {x \in R|\,\,x > 10} \right\}\\
\Rightarrow A \cup B = \left\{ {x \in R|\,\,x > 4} \right\}.
\end{array}\)