# Rationalising denominator

• Aug 28th 2010, 08:18 PM
99.95
Rationalising denominator
Hi,
If i have : [attached image]

how do i obtain the other result?
Is it by rationalising denominator?
i thought that when you rationalise the denominator by multiplying it by
sqrt.k the numerator becomes: k.sqrt.k ?

Bit of confusion.
(The full question involves differentiating, however, my algebra skills have let me down :|)
thanks

NOTE: SORRY, that should be a 'k' inside the root sign, not 'x'.
• Aug 28th 2010, 08:31 PM
undefined
Quote:

Originally Posted by 99.95
Hi,
If i have : [attached image]

how do i obtain the other result?
Is it by rationalising denominator?
i thought that when you rationalise the denominator by multiplying it by
sqrt.k the numerator becomes: k.sqrt.k ?

Bit of confusion.
(The full question involves differentiating, however, my algebra skills have let me down :|)
thanks

NOTE: SORRY, that should be a 'k' inside the root sign, not 'x'.

Multiply numerator and denominator by sqrt(k). There will be a k you can cancel.
• Aug 28th 2010, 08:40 PM
99.95
thank you, i'm an idiot -_-
• Aug 28th 2010, 09:26 PM
$\displaystyle\frac{k}{2\sqrt{k}}=\frac{\sqrt{k}\sq rt{k}}{2\sqrt{k}}$