# LIMITS, not able to factor

1. Sep 16, 2008

### susan__t

the question is:

The limit as x approaches -2 when f(x)= x+2/x3+8

I cannot factor it, or use a limit law (to my knowledge) and am simply having trouble finding the answer which is suppose to be 1/12.

Any help getting me started would be greatly appreciated

Susan

2. Sep 16, 2008

### morphism

Can you factor a^3 - b^3?

3. Sep 16, 2008

Actually, you need to factor

$$a^3 + b^3$$

$$f(x) = \frac{x+2}{x^3 + 8}$$
)

4. Sep 16, 2008

### morphism

It's the same thing, because a^3 + b^3 = a^3 - (-b)^3.

The reason I chose to use difference instead of sum is because difference is usually more familiar, and might spark the right idea.

5. Sep 16, 2008

Certainly true and obvious when you know the steps that are to be done. I've been teaching mathematics and statistics long enough to realize that occasionally a student may not make that connection - not because of lack of ability, but because of frustration, nerves, haste, or many other reasons. In a situation like this, a little more direct approach can't hurt.
My previous post was not intended to be smarmy - I hope that no offense was taken, because none was meant.

6. Sep 16, 2008

### susan__t

thank you so much both of you, I really had no idea what I could branch out of the equation and I would never have found that on my own

7. Sep 17, 2008