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Math Help - factorising indices

  1. #1
    Senior Member Mukilab's Avatar
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    factorising indices

    Am I right in saying you cannot factorise the expression x^n+1 where n if greater or equal to 3 is odd?

    apart from x^3 which would be (x+1)(x^2-x+1)
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  2. #2
    Senior Member yeKciM's Avatar
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    Quote Originally Posted by Mukilab View Post
    Am I right in saying you cannot factorise the expression x^n+1 where n if greater or equal to 3 is odd?

    apart from x^3 which would be (x+1)(x^2-x+1)
     x^5 +1  = (x+1) (x^4-x^3+x^2-x+1)

     x^7 +1 = (x+1) (x^6-x^5+x^4-x^3+x^2-x+1)

     x^9 +1 = (x+1) (x^2-x+1) (x^6-x^3+1)


    Last edited by yeKciM; September 8th 2010 at 11:58 AM.
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