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a/ \(\left\{a\right\};\left\{b\right\};\left\{a;b\right\};\varnothing\)
b/ \(\left\{1\right\};\left\{2\right\};\left\{3\right\};\left\{1;2\right\};\left\{1;3\right\};\left\{2;3\right\};\left\{1;2;3\right\};\varnothing\)
c/ \(\left\{0\right\};\left\{1\right\};\left\{2\right\};\left\{3\right\};\left\{0;1\right\};\left\{0;2\right\};\left\{0;3\right\};\left\{1;2\right\};\left\{1;3\right\};\left\{2;3\right\};\left\{0;1;2\right\};\left\{1;2;3\right\};\left\{0;2;3\right\};\left\{0;1;3\right\};\left\{0;1;2;3\right\};\varnothing\)
d/ \(\left\{1\right\};\left\{-2\right\};\left\{1;-2\right\};\varnothing\)
Câu 2:
\(X\subset\left\{-3;-2;0;1;2;3\right\}\)
\(X\subset\left\{-1;0;1;2;3;4\right\}\)
DO đó: \(X=\left\{0;1;2;3\right\}\)
Các tập con là {0}; {1}; {2}; {3}; rỗng; {0;1}; {0;2}; {0;3}; {1;2}; {1;3}; {2;3}; {0;1;2}; {1;2;3}; {0;1;3}; {0;1;2;3}
a) \(A=\left\{0;1;2;3;...;13\right\}\)
b) Ta có: \(x^2+3x-9=0\)
\(\Leftrightarrow\left(x-\frac{-3+3\sqrt{5}}{2}\right)\left(x+\frac{3+3\sqrt{5}}{2}\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{-3+3\sqrt{5}}{2}\\x=\frac{-3-3\sqrt{5}}{2}\end{cases}}\)
c) \(C=\left\{-7;-6;-5;...;5;6;7\right\}\)
a: A=(-7/4; -1/2]
\(B=\left(-\dfrac{9}{2};-4\right)\cup\left(4;\dfrac{9}{2}\right)\)
\(C=\left(\dfrac{2}{3};+\infty\right)\)
b: \(\left(A\cap B\right)\cap C=\varnothing\)
\(\left(A\cup C\right)\cap\left(B\A\right)\)
\(=(-\dfrac{7}{4};-\dfrac{1}{2}]\cup\left(\dfrac{2}{3};+\infty\right)\cap\left[\left(-\dfrac{9}{2};-4\right)\cup\left(4;\dfrac{9}{2}\right)\right]\)
\(=\left(4;\dfrac{9}{2}\right)\)
\(x^4-16\left(x^2-1\right)=0\Leftrightarrow x^4-16x^2+16=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2=8+4\sqrt{3}\\x^2=8-4\sqrt{3}\end{matrix}\right.\)
\(\Rightarrow A=\left\{-\sqrt{6}-\sqrt{2};\sqrt{2}-\sqrt{6};\sqrt{6}-\sqrt{2};\sqrt{2}+\sqrt{6}\right\}\)
\(2x\le9\Rightarrow x\le\frac{9}{2}\Rightarrow B=\left\{0;1;2;3;4\right\}\)
Bạn coi lại đề, tập hợp A nhìn rất có vấn đề :)