Câu 14: `bbD`
`EEA<=> 2m<=m+3`

`<=> m<=3`

Xét `A nn B =`$\varnothing$

`<=> [2m; m+3] sub (-2; 4]`

`<=> {(-2<2m), (m+3<=4):}`

`<=> {(-1<m), (m<=1):}`

`=>A nn B !=`$\varnothing$ `<=> [(m<=-1),(m > 1):}`

Kết hợp ĐK `=> [(1<m<=3), (m<=-1):}`

Câu 16: `bbD`

`a > -1=> 2a<3a+1=>B !=`$\varnothing, \forall a$

Xét `A nn B =`$\varnothing$ với `A = [0; 5]`

`<=> [(3a+1<0), (2a >= 5):}`

`<=> [(a<-1/3), (a >= 5/2):}`

`=>A nn B !=`$\varnothing$ `<=> -1/3<=a<5/2`