Factorisation

Natkirky · 2010-10-31 03:40:26

Hi Can i please have help simplifying this equation:

(x² - y²)² + 4xy(x+y)²

I am in 1 year at uni however, it's been 4 years since i done maths and i was never great at factorising.

I understand that i am looking for a common factor the solution i have is (x+y)^4 I have tried everything i can think of and can't get this.

Thank you

bobbym · 2010-10-31 04:55:34

Hi Natkirky;

You have to play with it a little and you have to know your common expansions or have a table of them.

Expand out the first term. You should know (x^2 - y^2) = (x-y)(x+y) So:

Pull out an (x +y)^2.

Now if you do not know (x+y)^2 = (x-y)^2 +4xy you can figure it like this.

You know that (x+y)^2 = x^2 + 2xy + y^2 and if you expand (x-y)^2 you get (x^2 - 2xy +y^2), subtract them.

So now you have another identity.

Take a look at A, that is what you have in the parentheses on the right. So substitute.

You are done.

I know I have made it look complicated because I wanted to explain where everything comes from. Just remember some simple identities.
Write them down for safekeeping:

Remember you have to practice to get any skill in anything!

Natkirky · 2010-10-31 05:35:03

Hi Bobbym,

Thanks a lot i missed the difference of squares in the first bracket as soon as i saw that i figured the rest out.

Thanks for the hints i did know these identities at one point hopefully it will all come back to me.

Thanks
Natalie

bobbym · 2010-10-31 05:48:27

Hi Natalie;

It will just keep working on it. Also drink plenty of chicken soup. Why, you might ask? The answer, because it tastes good.

Glad to help!

Math Is Fun Forum

#1 2010-10-31 03:40:26

Factorisation

#2 2010-10-31 04:55:34

Re: Factorisation

#3 2010-10-31 05:35:03

Re: Factorisation

#4 2010-10-31 05:48:27

Re: Factorisation

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