Question

Cho CʀA = ( - vô cực ; 5 ] ᑌ ( 7; + vô cực) CʀB = (-3;4] a) tìm A và B b) tìm AᑌB, A giao B, A\B, B\A

Answer 1

\(\left\{{}\begin{matrix}C_RA=\left(-\infty;5\right)\cup\left(7;+\infty\right)\\C_RB=(-3;4]\end{matrix}\right.\)

a) \(C_RB=(-3;4]\)

\(\Leftrightarrow B=(-\infty;-3]\cup\left(4;+\infty\right)\)

\(C_RA=\left(-\infty;5\right)\cup\left(7;+\infty\right)\)

\(\Leftrightarrow A=\left[5;7\right]\)

b) \(A\cup B=(-\infty;-3]\cup\left(4;+\infty\right)\)

\(A\cap B=\left[5;7\right]\)

\(A\)\\(B=\varnothing\)

\(B\)\\(A=(-\infty;-3]\cup\left(4;5\right)\)