Question

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

a) x-3/x^2-4
b) x-3/x^2+4
c) x^2-4/x-3
d) x^2+4/x-3

Answer 1

look at the denomenator and see which ones become 0 when -2 is subed for x
cause you can't divide by 0

A. 4-4=0, this has -2 excluded
B. 4+4=8, this is fine, -2 is not excluded
C. -2-3=-5, this is find, -2 is not excluded
D. same as above


answer is A

Answer 2

Option A.
`(x-3)/(x^(2)-4 )`

Explanation:

The excluded value of any function comes from the denominator.There can not be a 0 in denominator as this will make the function undefined.

To find the x value that will make the denominator 0 we put the denominator =0 and solve for x .

A)
`x^(2) -4=0`

Or (x+2)(x-2)=0

Solving for x :

x+2=0 x-2=0

x=-2. x=2.

In this function x=-2 will make the denominator 0 and hence will be the excluded value.