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Math Help - Really really basic factorization

  1. #1
    Member
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    Really really basic factorization

    Hi all,

    I feel pretty dumb posting this up, but here we go.

    Factorise -
     9a^2 - 4b^2 + 12a + 8b

    I don't know why, I just never seem to be able to find the right combination for these.

    I know we're meant to type out a common factor, I can't spot it though

    I.e. for ax + bx + ay + by = a (x + y) + b (x + y) -> (a + b)(x + y)

    Anyone want to point out the obvious combination for me?
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  2. #2
    MHF Contributor
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    Quote Originally Posted by Peleus View Post
    Hi all,

    I feel pretty dumb posting this up, but here we go.

    Factorise -
     9a^2 - 4b^2 + 12a + 8b

    I don't know why, I just never seem to be able to find the right combination for these.

    I know we're meant to type out a common factor, I can't spot it though

    I.e. for ax + bx + ay + by = a (x + y) + b (x + y) -> (a + b)(x + y)

    Anyone want to point out the obvious combination for me?

    Erm , i think this will work .

    (9a^2-4b^2)+(12a+8b)

    =(3a+2b)(3a-2b)+4(3a+2b)

     <br />
=(3a+2b)(3a-2b+4)<br />
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  3. #3
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    Sep 2007
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    Thanks mate, I knew I was missing something. Just wasn't in the form I was expecting. I really need to stop expecting certain answers out of math questions and look at them objectively

    Appreciate it.
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