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Math Help - Factorising Quadratic Equations

  1. #1
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    Factorising Quadratic Equations

    Hello, trying to factorise:

    x^2-5x-6

    So far i've got:

    AC = -6, so x^2+x-6x-6 = x(x+1)-6(x+1)

    Now getting to that point all makes sense to me, however in my textbook it says 'x+1 is a factor of both terms, so take that outside the bracket', leaving the answer as (x+1)(x-6). I don't understand how they got from x(x+1)-6(x+1) to (x+1)(x-6). Any help would be appreciated, thanks.
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  2. #2
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    Quote Originally Posted by Aaron01424 View Post
    Hello, trying to factorise:

    x^2-5x-6

    So far i've got:

    AC = -6, so x^2+x-6x-6 = x(x+1)-6(x+1)

    Now getting to that point all makes sense to me, however in my textbook it says 'x+1 is a factor of both terms, so take that outside the bracket', leaving the answer as (x+1)(x-6). I don't understand how they got from x(x+1)-6(x+1) to (x+1)(x-6). Any help would be appreciated, thanks.
    Can you factorise xA - 6A ?
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  3. #3
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    Since both terms are multiplied by (x+1), you can just take x+1 outside the brackets to give x^2-5x-6=(x-6)(x+1).
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  4. #4
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    Quote Originally Posted by mr fantastic View Post
    Can you factorise xA - 6A ?
    Yeah, A(x-6).

    Quote Originally Posted by Showcase_22 View Post
    Since both terms are multiplied by (x+1), you can just take x+1 outside the brackets to give x^2-5x-6=(x-6)(x+1).
    Yeah, that's what it says in the book. Maybe i'm overcomplicating it, but I don't understand what you do when you take it out of the brackets.
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  5. #5
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    Quote Originally Posted by Aaron01424 View Post
    Yeah, A(x-6).



    Yeah, that's what it says in the book. Maybe i'm overcomplicating it, but I don't understand what you do when you take it out of the brackets.
    OK. Now replace A with (x + 1).
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  6. #6
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    Aha. I see, great. Cheers.
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