# I am stuck on evaluating the limit of a rational function

1. Mar 8, 2010

### Charismaztex

1. The problem statement, all variables and given/known data

Evaluate the limit: $$lim_{(x)\rightarrow(2)}\frac{x^2+x-6}{sqrt(x+4)-sqrt(6)}$$

2. Relevant equations

N/A

3. The attempt at a solution

I've drawn the graph which indicates that the at x=2, y=0, so 0 would seem to be the limit.
I could not, however, get the limit expression by algebraic manipulation to get to 0.

First of all, I rationalized the denominator to give x-2, which is a common factor of the numerator and the denominator. But canceling this, I am left with the expression:

$$lim_{(x)\rightarrow(2)}((x+3)(sqrt(x+4)+sqrt(6))$$

after the $$lim_{(x)\rightarrow(2)}\frac{x-2}{x-2}$$ comes to 1.

I may have missed something crucial, so I just can't get the limit to be 0

Any help is greatly appreciated,
Charismaztex

2. Mar 8, 2010

Try again - the limit is not zero. Your simplification is correct.

3. Mar 8, 2010

### HallsofIvy

That is NOT, by the way, a rational function.

4. Mar 8, 2010

### Charismaztex

@statdad The graph shows that at x=2, y=0. How is this explained?

@ HallsofIvy Why not? I thought it can be expressed in the form p/q where p and q are real. Or if there are irrational numbers anywhere, does this make it void?

5. Mar 8, 2010

### Hurkyl

Staff Emeritus
A rational function is a ratio of polynomials.

6. Mar 8, 2010