Question

Tìm x

(x-2)(7-x)>0

Answer 1

`(x-2)(7-x)>0`

`<=>(x-2)(x-7)<0`

Vì `x-2>x-7`

`=>x-2>0,x-7<0`

`=>x>2,x<7`

`=>2<x<7`

Nếu có `x in Z`

`=>x in {3,4,5,6}`

Answer 2

(x-2)(7-x)>0

=> x-2>0 hoặc 7-x>0

* x-2>0 => x>2

*7-x>0 => x<7

Answer 3

`(x-2)(7-x)<0`

`<=>(x-2)(x-7)<0`

`<=>2<x<7`

`<=>x in {3,4,5,6}`