Question

设全集为R，集合A=｛X|-1≤X＜3｝，B=｛X|2X-4≥X-2｝求：A∪B,CR(A∩B)

Answer 1

A={x|-1≤x<3} B={x|2x-4≥x-2} ={x| x ≥ 2 } A∪B = {x|-1≤x<3} ∪ {x| x ≥ 2 } = { x | x≥ -1 } CR（A∩B) = R - (A∩B ) = R -( {x|-1≤x<3} ∩ {x| x ≥ 2 } ) =R - {x| 2 ≤x<3} = { x | x< 2 or x ≥ 3 } B∪C=C => B is subset of C C={x|2x+a＞0} = { x| x > -a/2 }