数学
已知集合A={X丨-1<=x<=7},B={X丨2-m<x<3m+1}若A∩B=B,求实数m的取值范围;2.已知集合A={y丨y²-(a²+a+1)y+a(a²+1)>0},B={y丨y²-6y+8<=0},若A∩B≠空集,求实数a的取值范围.

2019-05-27

已知集合A={X丨-1<=x<=7},B={X丨2-m<x<3m+1}若A∩B=B,求实数m的取值范围;
2.已知集合A={y丨y²-(a²+a+1)y+a(a²+1)>0},B={y丨y²-6y+8<=0},若A∩B≠空集,求实数a的取值范围.
优质解答
由题意可知:3m+1>2-m,
2-m>=-1,
3m+1<=7;
得: 1/4假设A∩B=空集,由A:ya²+1;B:2<=y<=4可知,
a>=2且a²+1>=4,则a<=-√3(根号3)或√3<=a<=2..
由题意可知:3m+1>2-m,
2-m>=-1,
3m+1<=7;
得: 1/4假设A∩B=空集,由A:ya²+1;B:2<=y<=4可知,
a>=2且a²+1>=4,则a<=-√3(根号3)或√3<=a<=2..
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