Question

设集合A={x丨丨x-a丨<1}B={x丨0<x<5 x∈R}若A∩B=∅求a取值范围

求准

Answer 1

集合A={x丨丨x-a丨<1}

|x-a|<1

==>

-1<x-a<1

==>

a-1<x<a+1

即A={x|a-1<x<a+1}

∵B={x丨0<x<5 x∈R}

A∩B=Φ

∴a+1≤0或a-1≥5

解得a≤-1或a≥6