When is a rational expression undefined?

1. 1 2 ­4 ­.5
2 0 ­3 0
3 ­2 ­2 1
4 ­4 ­1 4
5 ­6 0 U
6 ­8 1 ­8
7 ­10 2 ­5
8 ­12 3 ­4
9 ­14 4 ­3.5
10 ­16 5 ­3.2
4.5 ­5 ­0.5 10
5.5 ­7 0.5 ­14
1

2. ­2x + 4
x ­ 5
­5 12 ­18 12
(­2x+4)/(x­5)
2

3. 2
where f(x), the numerator, = 0.
all Reals except 5
where g(x), the denominator, = 0
Find where the denominator = 0
3

4. x = 0 2x ­ 5 = 0
x = 2.5
x = ­7, 5
4

5. n(x) is the numerator, k(x) is the denominator
5