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#1 2005-05-19 13:41:25

im really bored
Member
Registered: 2005-05-12
Posts: 76

Some quick help please

factor completely:   128x^6  -  2y^6

I can expand it to:   2(8x^3 + y^3)(8x^3 - y^3)

I know it can be expanded more but how would that go?

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#2 2005-05-19 17:53:29

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,534

Re: Some quick help please

2(8x^3 + y^3)(8x^3 - y^3)

Hmm .... the two similar terms can be further factored like this

(2x+y)*(4x^2-2xy+y^2) ==> 8x^3 - 4x^2y + 2xy^2 + 4x^2y - 2xy^2 + y^3 ==> 8x^3 + y^3 
(2x-y)*(4x^2+2xy+y^2) ==> 8x^3 + 4x^2y + 2xy^2 - 4x^2y - 2xy^2 - y^3 ==> 8x^3 - y^3

So:

2(2x+y)*(4x^2-2xy+y^2)(2x-y)*(4x^2+2xy+y^2)


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#3 2005-05-20 10:46:39

im really bored
Member
Registered: 2005-05-12
Posts: 76

Re: Some quick help please

Thanks, I was having some mental issues at the time...

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