# Derivative Rationalizing

#### mathitup

##### New member
Code:
__1________       -    ___1_____
√(x+h)² - 5             √(x²-5)
________________________________
h
sorry about that, i hope this helps
I need to find out how to rationalize this

#### pka

##### Elite Member
First, simply the fraction $$\displaystyle \frac{{\sqrt {x^2 - 5} - \sqrt {\left( {x + h} \right)^2 - 5} }}{{h\left( {\sqrt {x^2 - 5} } \right)\left( {\sqrt {\left( {x + h} \right)^2 - 5} } \right)}}$$.
Then rationalize by multiplying numerator and denominator by $$\displaystyle \sqrt {x^2 - 5} + \sqrt {\left( {x + h} \right)^2 - 5}$$

You can get help with TEX by going to the Forum Help tab at the top.
If you use Windows, I urge you to look into TeXaide.

#### mathitup

##### New member
so what happened to the 1's on top in the first part of the question, how were you able to get rid of those?

#### Unco

##### Senior Member
Cross multiply.

By the way, if you ever want to get the code tags to work, type it in notepad and copy over - it looks like it should that way.

#### mathitup

##### New member
oh alright thanks alot, so i just cross the top as it was its own equation? and then its all overe h and then i multiply by the roots to rationalize?