Question

tìm x biết x+5/x+1 < 1

Answer 1

`(x+5)/(x+1)<1`

`(x+1+4)/(x+1)<1`

`1+4/(x+1)<1`

`4/(x+1)<0`

`x+1<0`

`x<-1`

Answer 2

`(x+5)/(x+1)<1`           ĐKXĐ : `x \ne -1`

`<=>(x+5)/(x+1)-1<0`

`<=>(x+5)/(x+1)-(x+1)/(x+1)<0`

`<=>(x+5-x-1)/(x+1)<0`

`<=>4/(x+1)<0`

`=>x+1<0`  ( vì `4>0` )

`<=>x<-1`

Kết hợp với ĐKXĐ : `x<-1`

Answer 3

Ta có: \(\dfrac{x+5}{x+1}< 1\)

\(\Leftrightarrow\dfrac{x+5-x-1}{x+1}< 0\)

\(\Leftrightarrow x+1< 0\)

hay x<-1