Tập hợp nào sau đây có đúng hai tập hợp con?
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Ta cần tìm tập hợp có đúng 2 tập con.
- Tập $\left\{1;4\right\}$ có các tập con là: $\varnothing, \left\{1\right\}, \left\{4\right\}, \left\{1;4\right\}$. Vậy có 4 tập con.
- Tập $\left\{1\right\}$ có các tập con là: $\varnothing, \left\{1\right\}$. Vậy có 2 tập con.
- Tập $\left\{\varnothing; 1\right\}$ có các tập con là: $\varnothing, \left\{\varnothing\right\}, \left\{1\right\}, \left\{\varnothing; 1\right\}$. Vậy có 4 tập con.
- Tập $\left\{\varnothing; 1; 4\right\}$ có 8 tập con.
Vậy đáp án là $\left\{1\right\}$.
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