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Math Help - Grade 8 Algebric Expressions

  1. #1
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    Grade 8 Algebric Expressions

    Ok, so I have this expression, and I need some help on it:

    15abc - ab + 3ab

    I'm guessing that first you go: ab + 3ab (cos ab= 1ab, and 3ab and ab are therefore like terms)

    That would then leave me with 15abc - 4ab

    That is what I understand so far, but can this expression be simplified further?
    If so, how ?

    THANKS!
    Last edited by JesseElFantasma; April 11th 2011 at 08:25 AM.
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  2. #2
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    Some may argue ab(15c - 4) is more simplified, but it's a matter of personal preference.
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  3. #3
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    Quote Originally Posted by NOX Andrew View Post
    Some may argue ab(15c - 4) is more simplified, but it's a matter of personal preference.
    Could you please explain that?
    Thanks!
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  4. #4
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    Quote Originally Posted by JesseElFantasma View Post
    15abc - ab + 3ab

    I'm guessing that first you go: ab + 3ab (cos ab= 1ab, and 3ab and ab are therefore like terms)
    The method is correct, but you missed a minus sign:
    15abc - ab + 3ab = 15abc + (-ab + 3ab) = 15abc + (2ab)

    Now notice that each term has a common ab in them. Thus
    15abc + 2ab = 15(ab)c + 2(ab) = 15c(ab) + 2(ab) = (15c + 2)ab

    (15abc = 15(ab)c = 15c(ab) due to the commutative property of real numbers.)

    -Dan
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  5. #5
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    Thank you Dan and Andrew!
    That really helped.
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