Question

  

Answer 1

\(A=\left\{-2;-1;1;2\right\}\)

\(B=\left\{0;1;2;3;4\right\}\)

\(B\backslash A=\left\{0;3;4\right\}\)

a.

\(X\subset B\backslash A\Rightarrow X=\varnothing;\left\{0\right\};\left\{3\right\};\left\{4\right\};\left\{0;3\right\};\left\{0;4\right\};\left\{3;4\right\};\left\{0;3;4\right\}\)

b.

\(A\backslash B=\left\{-2;-1\right\}\)

\(\Rightarrow\left\{-2;-1\right\}\subset X\)

Mà X có đúng 2 phần tử \(\Rightarrow X=\left\{-2;-1\right\}\)