若“0若“0
若“0集合A=(0,3),集合B=(a-3,2a+1)由题意得:A真包含于B所以:a-3≦0 得:a≦32a+1≧3 得:a≧1综上,a的取值范围是:1≦a≦3
a-3<=0 2a+1>=3a<=3 a>=1 1<=a<=3