find all numbers for whic rationa expression is undefined

[shea14shea]

Please help me find an answer.
find all numbers for which the rational expressioned is undefined
(q^3-9q)/(q^2-64)

 

[JuicyBurger]

Please help me find an answer.
find all numbers for which the rational expressioned is undefined
(q^3-9q)/(q^2-64)

Well, the only way this rational expression can be undefined is if there is division by zero. So, you tell me... for which values of q will this be true...

\(\displaystyle \frac{q^3-9q}{q^2-64} = \frac{q^3-9q}{0}\)

 

[shea14shea]

Is t q=8? I am so lost!!!!

 

[JuicyBurger]

Is t q=8? I am so lost!!!!

Close. I assume you set it up as...

\(\displaystyle q^2 = 64\)

Now when you take the square root of both sides you get:
\(\displaystyle q = \pm 8\)

 

[shea14shea]

Thanks, that made it much easier to figure out. Why is it it greater than or equa to and not just equal? If it is greater than 8 won't that make it a negative number insted of zero?

 

[JuicyBurger]

Thanks, that made it much easier to figure out. Why is it it greater than or equa to and not just equal? If it is greater than 8 won't that make it a negative number insted of zero?

I don't understand your question, the answer is \(\displaystyle \pm8\) as in \(\displaystyle -8 \ \ or \ \ 8\)

 

[shea14shea]

Oh, that makes complete sense! lol sorry!