# rationalise

• January 15th 2010, 08:18 AM
andyboy179
rationalise
i need to rationalise the denominators of this $\frac{1}{\sqrt{3}}$

can someone explain what i need to do?
• January 15th 2010, 09:08 AM
Multiply by $\frac{\sqrt{3}}{\sqrt{3}}$ to change the denominator to an integer.
• January 15th 2010, 09:19 AM
andyboy179
Quote:

Multiply by $\frac{\sqrt{3}}{\sqrt{3}}$ to change the denominator to an integer.

i was gonna post because i thought it was that, so the answer would be Attachment 14832
• January 15th 2010, 09:23 AM
VonNemo19
yes, but do you need the 1?
• January 15th 2010, 09:26 AM
Yes, that's it,

beyond that,
you would use the "surd conjugate" when the denominator is
composed of an integer and square root....

example

$\frac{1}{2+\sqrt{3}}=\frac{1}{2+\sqrt{3}}\ \frac{2-\sqrt{3}}{2-\sqrt{3}}$
• January 15th 2010, 10:16 AM
andyboy179
Quote:

Originally Posted by VonNemo19
yes, but do you need the 1?

no!!!
• January 15th 2010, 07:57 PM
differentiate
understand that rationalise the denominator means to change the denominator so that it is a rational number (i.e. no surds!)

some people rote learn maths and decide to multiply top and bottom by the denominator, which is obviously not the case, as sometimes you need to multiply by the surd conjugate.
so yeah