# Help with a mathematics question - rationalising

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I'm supposed to rationalise this question as follows, but I'm unsure of how to do it

Could anyone help me with the method?

12√a

--------------------------

(√a + 2)² - (√a - 2)²

I got the answer 12√a but I'm pretty sure it's not correct

Thanks in advance

Could anyone help me with the method?

12√a

--------------------------

(√a + 2)² - (√a - 2)²

I got the answer 12√a but I'm pretty sure it's not correct

Thanks in advance

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#2

(Original post by

I'm supposed to rationalise this question as follows, but I'm unsure of how to do it

Could anyone help me with the method?

12√a

--------------------------

(√a + 2)² - (√a - 2)²

I got the answer 12√a but I'm pretty sure it's not correct

Thanks in advance

**BerrySpecial**)I'm supposed to rationalise this question as follows, but I'm unsure of how to do it

Could anyone help me with the method?

12√a

--------------------------

(√a + 2)² - (√a - 2)²

I got the answer 12√a but I'm pretty sure it's not correct

Thanks in advance

Upload your working if problems.

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(Original post by

Use the difference of two squares on the denominator.

Upload your working if problems.

**mqb2766**)Use the difference of two squares on the denominator.

Upload your working if problems.

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#4

(Original post by

Thing is they're squared so I'm unsure of how to use the difference of two squares

**BerrySpecial**)Thing is they're squared so I'm unsure of how to use the difference of two squares

You'd get the same result of you expanded and simplified.

Last edited by mqb2766; 1 week ago

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#5

(Original post by

I got the answer 12√a but I'm pretty sure it's not correct

**BerrySpecial**)I got the answer 12√a but I'm pretty sure it's not correct

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#6

**BerrySpecial**)

I'm supposed to rationalise this question as follows, but I'm unsure of how to do it

Could anyone help me with the method?

12√a

--------------------------

(√a + 2)² - (√a - 2)²

I got the answer 12√a but I'm pretty sure it's not correct

Thanks in advance

Can you post your working? (Your answer is incorrect)

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I've successfully figured out how to do the expansion brackets

12√a

----------

(a+4√a+4)-(a-4√a+4)

= 12√a

----------

8√a

But I can't for the life of me figure out how to find the difference between squares which I need to do

12√a

----------

(a+4√a+4)-(a-4√a+4)

= 12√a

----------

8√a

But I can't for the life of me figure out how to find the difference between squares which I need to do

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#8

(Original post by

I've successfully figured out how to do the expansion brackets

12√a

----------

(a+4√a+4)-(a-4√a+4)

= 12√a

----------

8√a

But I can't for the life of me figure out how to find the difference between squares which I need to do

**BerrySpecial**)I've successfully figured out how to do the expansion brackets

12√a

----------

(a+4√a+4)-(a-4√a+4)

= 12√a

----------

8√a

But I can't for the life of me figure out how to find the difference between squares which I need to do

The difference of squares is:

Applying that here is just a short-cut (although not that much of one):

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(Original post by

You don't to solve this question. What you have done, so far, is correct.

The difference of squares is:

Applying that here is just a short-cut (although not that much of one):

**RogerOxon**)You don't to solve this question. What you have done, so far, is correct.

The difference of squares is:

Applying that here is just a short-cut (although not that much of one):

I simply failed to realise that (√a+2)^ is one "number" so to say in the a^ - b^

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