Question

The function y=x/x^2-9 is undefined when the value of x is which of the following?
A. 0 or 3
B. 3 or -3
C. 3 only
D. -3 only

Answer 1

What is the denominator?

Answer 2

\[x^2 - 9\]

Answer 3

Are there any values that a denominator cannot be?

Answer 4

nope

Answer 5

Im confused

Answer 6

Remember that dividing by 0 is meaningless so the denominator cannot be 0

Answer 7

That is a general rule you should learn.

Answer 8

ok

Answer 9

So once we realize that it is illegal for the denominator to be 0 we need to find the illegal values of x that result in a denominator of 0

Answer 10

ok
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Answer 11

So now the question is : what x value or values will make x^2-9 = 0

Answer 12

So I can see that something minus 9 is 0 and that something is 9.

Answer 13

So if x^2 is 9, the denominator is 0.

Answer 14

so a

Answer 15

So if x^2 is 9, what is x?

Answer 16

0^2-9 is not 0

Answer 17

We could make it easier by saying:
\[x^2-9=(x-3)(x+3)=0\]

Answer 18

\[x-3=0 or x+3=0\]

Answer 19

\[x=3 or x=-3\]

Answer 20

so yues a

Answer 21

So I would say that B is the correct answer.

Answer 22

k