# Homework Help: Limits help

1. Oct 15, 2005

### powp

can anybody help me with these two question for finding limits:

1. lim h -> 0 ((3+h)^-1 - 3^-1)/h
2. lim x -> -4- |x+4|/x+4

2. Oct 15, 2005

### shmoe

1. looks an awful lot like the kind of limit you find in the definition of the derivative. If you haven't seen derivatives yet (or even if you have) try finding a common demoninator to simplify (3+h)^(-1) - 3^(-1)

2.you're interested in values of x that are less than -4. Use this to simplify the absolute value.

3. Oct 15, 2005

### powp

for number one if I make it so that I only have positive exponents and simplify I end up with

1 /(9 + 3h) now if I plug in 0 the result is 1 / 9. Is this correct?

4. Oct 15, 2005

### Math Is Hard

Staff Emeritus
I think you might have a sign error. Check this step in the numerator and tell me what you think:
(3-(3+h))/(9 + 3h) should distribute as (3-3-h)/(9 + 3h) or -h/(9 +3h)

5. Oct 15, 2005

### powp

yeah it looks like I did make an error should be -1/9? right?

6. Oct 15, 2005

### Math Is Hard

Staff Emeritus
That's what I got, but maybe one of the local mathletes will stop by and verify.