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Math Help - VERY simple question about solving equations

  1. #1
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    VERY simple question about solving equations

    Hello.

    This question may seem a little unusual but I'm desperate about it.

    So I have this equation:

    y = (x^2 + 3x) - (2x + 3)(x - 1)

    my question is: do I have to first apply the minus sign, or do the parenthesis first? I'm really confused about it and I feel ashamed (really! )

    Can you please show me how to solve this? Thank you
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  2. #2
    MHF Contributor Siron's Avatar
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    Re: VERY simple question about solving equations

    I guess you have to solve:
    0=(x^2+3x)-(2x+3)\cdot (x-1)
    The multiplication precede the subtraction.
    First expand (2x+3)\cdot (x-1).
    So you'll have something like:
    0=(x^2+3x)-(...x^2+...x+...)
    The brackets are important!
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  3. #3
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    Re: VERY simple question about solving equations

    Please Excuse My Dear Aunt Sally!

    Calculations inside (P)arentheses are done first, then (E)xponents, then (M)ultiplication and (D)ivision, and lastly (A)ddition and (S)ally.
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  4. #4
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    Re: VERY simple question about solving equations

    In that case we would have :

    y = (x^2 + 3x) - (2x + 3)(x - 1)

    y = (x^2 + 3x) - (2x^2 + x - 3)

    Now I apply the minus in :

    y = (x^2 + 3x - 2x^2 - x + 3) ==> -x^2 + 2x + 3

    right? I don't think so
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  5. #5
    MHF Contributor Siron's Avatar
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    Re: VERY simple question about solving equations

    Yes, that's right!
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