# Homework Help: Limit question

1. Jul 24, 2009

### 3.141592654

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

Use this limit for the following problems: lim as h approaches 0 of [f(x+h)-f(x)]/h.

f(x)=$$\sqrt{x}$$, x=7

2. Relevant equations

3. The attempt at a solution

lim as h approaches 0 of [f(x+h)-f(x)]/h

= lim as h approaches 0 of ($$\sqrt{7+h}$$-$$\sqrt{7}$$)/h

I'm having trouble simplifying the numerator, is there any way to get rid of the square roots in the numerator? Thank you.

2. Jul 25, 2009

### Office_Shredder

Staff Emeritus
Rationalize the numerator

$$\frac{ (\sqrt{7+h} - \sqrt{7})( \sqrt{7+h} + \sqrt{7})}{h( \sqrt{7+h} + \sqrt{7}}$$