# Rationalizing the Denominator

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• Feb 2nd 2009, 08:01 AM
Dickson
Rationalizing the Denominator
x^2 / (Square Root(x+1)) - (Square Root(x-1))

How to I multiply the conjugate on the bottom? I really just don't know how to do it
• Feb 2nd 2009, 08:13 AM
mathaddict
Re :
$
\frac{x^2}{\sqrt{x+1}-\sqrt{x-1}}$

Multiply the top and bottom by $\frac{\sqrt{x+1}+\sqrt{x-1}}{\sqrt{x+1}+\sqrt{x-1}}$

and hence it equals $\frac{x^2}{2}(\sqrt{x+1}+\sqrt{x-1})$

Use $(a+b)(a-b)=a^2-b^2$