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Thread: factorise

  1. #1
    Junior Member
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    Exclamation factorise

    please fully factorise:

    49-(x-4)^2
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  2. #2
    Junior Member
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    49-(x-4)^2

     <br />
49-(x-4)(x-4)<br />

     <br />
49-(x^2-8x+16)<br />

     <br />
49-x^2+8x-16<br />

     <br />
-x^2+8x+33<br />

     <br />
(-x+11)(x+3)<br />
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  3. #3
    MHF Contributor

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    But why in the world would you multiply something you want to factor?

    Tessarina, one of the easiest factoring formulas is the "difference of squares" formula: a^2- b^2= (a- b)(a+ b).

    Here, a^2= 49= 7^2 and (x-4)^2.

    49- (x-4)^2= (7- (x-4))(7+ (x-4))= (11- x)(3+ x).
    Last edited by mr fantastic; Feb 25th 2010 at 01:36 AM. Reason: Fixed math tag
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