Question

For which rational expression is -2 an excluded value of x?

Answer 1

`x^2-3/x^2-4`

Explanation:

An excluded value of x for any rational function or expression is when you have any value of x that makes the value of the function undefined. Thus, these values ​​must be excluded from the domain of the function.

in order to know if a value is an excluded value you have to calculate it in the expression:

x=-2

`x^2-3/x^2-4`=
`(-2)^2-3/(-2)^2-4`=
`4-3/4-4`= function undefined (because denominator 0 is undefined)

`x-3/x^2+4`=
`-2-3/(-2)^2+4`=
`-5/8`=function defined

`x^2-4/x-3`=
`(-2)^2-4/-2-3`=
`0`=function defined

`x^2+4/x-3`=
`(-2)^2+4/-2-3`=
`8/-5`=function defined

Answer 2

The first choice,
`(x-3)/(x^(2)-4 )`

Explanation:

Excluded value means that the value of x will make the denominator 0.

(-2)² - 4 = ?

4 - 4 = 0.

Therefore, it's the first choice–
`(x-3)/(x^(2)-4 )`