4.
\(A=\left\{1;2;3\right\}\) ; \(B=\left\{0;1;2;3\right\}\) ; \(C=[0;+\infty)\) ; \(D=\left\{\dfrac{1}{2};3\right\}\)
\(\Rightarrow A\subset B\) ; \(A\subset C\); \(B\subset C\) ; \(D\subset C\)
5.
\(A=\left\{\dfrac{1}{2};2\right\}\) ; \(B=\left\{\dfrac{1}{3};2\right\}\)
\(A\cap B=\left\{2\right\}\) ; \(A\cup B=\left\{\dfrac{1}{3};\dfrac{1}{2};2\right\}\)
\(A\backslash B=\left\{\dfrac{1}{2}\right\}\) ; \(B\backslash A=\left\{\dfrac{1}{3}\right\}\)
7.
Các tập con:
\(\varnothing;\left\{a\right\};\left\{b\right\};\left\{c\right\};\left\{d\right\};\left\{a;b\right\};\left\{a;c\right\};\left\{a;d\right\};\left\{b;c\right\};\left\{b;d\right\};\left\{c;d\right\}\)
\(\left\{a;b;c\right\};\left\{a;b;d\right\};\left\{a;c;d\right\};\left\{b;c;d\right\};\left\{a;b;c;d\right\}\)
giúp em câu c và d với ạ 😢
