学帮网已知集合A={x|1/8
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已知集合A={x|1/8<=2^(x+1)<=16},B={x|m+1<=x<=3m-1}(1)求集合A（2）若B包含于A,求实数m的取值范围
请写出过程还有易错点谢谢
(1)
A={x| 1/8<=2^(x+1)<=16}
= { x| 2^(-3)<= 2^(x+1) <=2^4 }
={ x| -4<= x <= 3 }
(2)
if B is subset of A
B={x|m+1<=x<=3m-1}
case 1: B is an empty set
m+1 > 3m-1
m<1
case 2: B is not an empty set (m >=1)
m+1>=-4 and 3m-1<=3
m >= -5 and m <=4/3
-5<=m <=4/3
solution for case 2:
m>=1 and "-5<=m <=4/3"
1<=m<=4/3
若B包含于A,求实数m的取值范围
case 1 or case 2
m<1 or 1<=m<=4/3
ie m<=4/3