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Maths help

z_o_e

ImageUploadedByStudent Room1483556529.298639.jpg

Need help please

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Reply 1

SherlockHolmes

Original post by z_o_e

Need help please

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For part (a):

27^{-\frac{2}{3}} = \frac{1}{27^{2/3}}

For part (b):

You need to rationalise the denominator.

Reply 2

z_o_e

Original post by SherlockHolmes

For part (a):

27^{-\frac{2}{3}} = \frac{1}{27^{2/3}}

For part (b):

You need to rationalise the denominator.

Got the first bit :smile:

Is it like this?
ImageUploadedByStudent Room1483556832.559614.jpg

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Reply 3

JaredzzC

Rationalising the denominator means making it a rational number (obvious, I know :biggrin:

) by multiplying it with what you did in the picture, it would still leave you with an irrational number on the bottom of the fraction.

To rationalise a square root, you multiply it by itself.

So to rationalise Root 2, you multiply it by root 2 which gives you 2. This is just one of the laws of indices which you should know. (Don't forget to multiply the top AND the bottom by root 2)

It will leave you with a fraction but once you simply everything, you should no longer be left with a fraction.

(edited 7 years ago)

Reply 4

z_o_e

Original post by JaredzzC

Rationalising the denominator means making it a rational number (obvious, I know :biggrin:

)

To rationalise a square root, you multiply it by itself.

So to rationalise Root 2, you multiply it by root 2 which gives you 2. This is just one of the laws of indices which you should know. (Don't forget to multiply the top AND the bottom by root 2)

It will leave you with a fraction but once you simply everything, you should no longer be left with a fraction.

This?

ImageUploadedByStudent Room1483557088.451128.jpg

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Reply 5

SherlockHolmes

Original post by z_o_e

Got the first bit :smile:

Is it like this?

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The denominator is still not a rational number if you do that. You want to multiply numerator and denominator by

\sqrt{2}

Reply 6

JaredzzC

Original post by z_o_e

This?

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Almost! root 2 x root 18 = root 36.

(edited 7 years ago)

Reply 7

z_o_e

Original post by JaredzzC

Almost! root 2 x root 18 = root 36.

Yeppp whats the next step x

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Reply 8

Uni12345678

Original post by z_o_e

Got the first bit :smile:

Is it like this?
ImageUploadedByStudent Room1483556832.559614.jpg

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For part (a) you should probably simplify 1/27^2/3 more as well because 27 has an integer cube root

Reply 9

JaredzzC

Original post by z_o_e

Yeppp whats the next step x

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now you need to get root 36 into (something multiplied by root 2) and then you can divide through by 2 to get rid of the fraction

(edited 7 years ago)

Reply 10

z_o_e

Original post by JaredzzC

now you need to get root 36 into (something multiplied by root 2) and then you can divide through by 2 to get rid of the fraction

I dont understand

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Reply 11

Eimmanuel

Study Forum Helper

Original post by z_o_e

Got the first bit :smile:

Is it like this?
ImageUploadedByStudent Room1483556832.559614.jpg

Posted from TSR Mobile

Rationalizing radical denominator means to multiply the numerator and denominator by the same radical.

For example

\dfrac{5}{\sqrt{3}} = \dfrac{\sqrt{3} \times 5}{\sqrt{3} \times \sqrt{3}}

Reply 12

Notnek

Original post by z_o_e

I dont understand

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Ignore that.

\sqrt{36} = ...

Reply 13

JaredzzC

Original post by z_o_e

I dont understand

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I think you need to revise your laws of indices for surds (this is what the question is testing you on)

If you look at the attachment, it shows how you can break up surds to get it into a different from.
This is what you'll need to do to the root 36 to try get b(root2)