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Solve this equation > 48÷2(9+3) = ?

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    talentedmonkeytalentedmonkey Posts: 2,639
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    2(9+3) is a totally different animal to 2x(9+3)

    In algebra you should treat 2(9+3) as (2x(9+3)) not 2x(9+3)

    therefore expanding the original question 48÷2(9+3) you get

    48÷(2x(9+3))
    If you want 288 then it should be written

    (48÷2)x(9+3)
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    [Deleted User][Deleted User] Posts: 193
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    2(9+3) is a totally different animal to 2x(9+3)

    In algebra you should treat 2(9+3) as (2x(9+3)) not 2x(9+3)

    therefore expanding the original question 48÷2(9+3) you get

    48÷(2x(9+3))
    If you want 288 then it should be written

    (48÷2)x(9+3)

    Exactly this. This is why I was on about algebra to start with! Glad someone else is thinking like me lol
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    AlphaKAlphaK Posts: 3,733
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    husted wrote: »
    There is no algebra here. Algebra is the concept of variables representing numbers. If there was an 'x' there it would be:

    2x(9+3) = 18x + 6x = 24x.

    When you are evaluating an expression, BODMAS is the convention even in algebra. Brackets first.

    All you have is a multiplication symbol:

    2x(9+3) = 2(9+3) = 18+6 = 24.


    Brackets first. Always.

    2x(9+3) does not give 18+ 6 ever
    it gives 2x (12)
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    [Deleted User][Deleted User] Posts: 101
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    It is bad maths to write such a non-algebraic sum without an operator between the number and the bracket, therefore the result is ambiguous. Please refine the question before answering.
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    [Deleted User][Deleted User] Posts: 533
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    288 :)
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    sodavlacsodavlac Posts: 10,607
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    Aware.
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    John259John259 Posts: 28,474
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    What I'm trying to say here is the 2(9+3) does not mean 2x(9+3) in the conventional sense. It means 2 lots of (9+3)
    But doesn't:
    2 lots of (9+3)
    mean exactly the same as:
    2x(9+3)
    ?

    a(b+c) means exactly the same thing as ax(b+c) (x being a multplication sign of course)
    and
    2(9+3)
    means exactly the same as
    2x(9+3)
    which is
    2x12
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    [Deleted User][Deleted User] Posts: 193
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    I give up. Can't be bothered to explain this to people who can't listen and be taught anything.Believe whatever the hell you want. I, and a lot of others know the answer is 2.
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    WombatDeathWombatDeath Posts: 4,723
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    OMFG!!!

    The very fact that there is no sign between the 2 and the brackets means that the 2 belongs to the brackets.

    People need to realise that BODMAS/BIDMAS is not the only mathematical theory going on here. There is also algebra to think of.

    EDIT (less confusing explanation)

    There is no multiplication sign to be put between the 2 and the brackets. 2(9+3) does not mean 2 x (9+3). It means (2x9)+(2x3). Anyone who has successfully studied algebra will know this.

    Sorry, that's just not true: 2(9+3) really does mean 2 x (9+3). And taken as an expression on its own it also means (2 x 9) + (2 x 3):

    a(b + c) = a x (b + c) = (a x b) + (a x c)

    We can hopefully all agree on that. The problem is that some of you are taking the above and forgetting the wider context of the original question, and you are assuming that because the 2 is next to the brackets it somehow 'belongs' to the expression inside the brackets. That assumption is simply not correct.

    48 ÷ 2(9+3) is simple short-hand for 48 ÷ 2 x (9+3). And, using BODMAS and left-to-right precedence (recall that multiplication and division have equal precedence), the answer is 288.

    Again, for the avoidance of doubt: omitting the multiplication sign between the 2 and the brackets does emphatically not imply that the 2 is in any sense linked to the brackets in a way which trumps the rules of precedence.

    (Qualification: maths degree; not that it matters because this is not grad-level maths. For those inclined to doubt my assertions, and indeed the rules of precedence themselves, I suggest that you post this question on a maths forum)
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    [Deleted User][Deleted User] Posts: 735
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    I appreciate that I'm above average intelligence but it's not that difficult... the answer is 2 for the reasons others have said... plus the below...

    ? = 48 ÷ 2(9+3)
    ? = 48 ÷ 2(12)
    ? x 2(12) = 48
    ? x 24 = 48
    ? = 48 ÷ 24
    ? = 2
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    psionicpsionic Posts: 20,188
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    I still make it 288 - my maths is rusty though :o

    But my calculator makes it 2 :confused:
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    5th Horseman5th Horseman Posts: 10,859
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    AlphaK wrote: »
    I was just messing as I believe the answer is 2
    Although as I wrote it there could be a third version

    48
    --- *9 + 2*3 = 24 * 9 + 2*3 = 216 + 6 = 222
    2

    Me too, just seeing how much confusion there can be. :D

    This is simple arithmetic, god help us if someone comes up with a maths puzzler.
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    John259John259 Posts: 28,474
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    The very fact that there is no sign between the 2 and the brackets means that the 2 belongs to the brackets.
    No, that's wrong. BODMAS doesn't say that, nor is there anything else in maths which says that. All the brackets say is to calculate what is inside them first.
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    lisa02lisa02 Posts: 1,105
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    D.M.N. wrote: »
    Given the debate this has created on two forums I visit (one frequently, one not so), I thought I'd bring this little debate over here.

    48÷2(9+3) = ?

    Simply, what's the answer? It'll become pretty clear after a few posts that some will get one answer and one will get another.

    I think it's two myself:

    48÷2(9+3)
    48÷2(12)
    48÷24
    = 2

    However, a lot are saying it is 288, by following this method (although I believe the above is technically more 'correct'):

    48÷2(9+3)
    24*(9+3)
    24*12
    = 288

    Which is right?

    2.

    BODMAS

    Brackets Over Division Multiplication Addition Subtraction.
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    lemoncurdlemoncurd Posts: 57,778
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    Out of interest, what is "z" in the following equation?

    z = 4y ÷ 2y

    Is it
    a) 2
    or
    b) 2y^2

    If you think the answer to the OP is 288, then I presume you would also go for b) here.
    Why? Because, replacing the immediate multipliers with a multiply sign (and I'll use "*" instead of "x"), you have:

    z = 4 * y ÷ 2 * y

    Breaking it down with left-to-right precedence for multiplication and division:

    4 * y ÷ 2 = 2y
    2y * y = 2y^2

    But if you consider "2y" to be an immediate multiplier (and "2(12)" to be the same), then suddenly your answer is different.
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    hustedhusted Posts: 5,287
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    People see to forget that:

    2ab + 2ac = 2a(b+c)

    So you cant say:

    2a(b+c) = 2ab + c. It's just wrong.
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    CoolboyACoolboyA Posts: 10,447
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    This whole thread just goes to show that maths is not always as "simple" as teachers make out.

    I hate maths with a passion and I'm so glad I have never had the misfortune to work with it since I left school!

    For what it's worth, I think the answer is 2... But then again, I was crap at maths.
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    John259John259 Posts: 28,474
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    lemoncurd wrote: »
    Out of interest, what is "z" in the following equation?

    z = 4y ÷ 2y
    The spaces are potentially confusing and could be wrongly taken to imply brackets around the 2y, so let's write it as
    4y÷2*y
    which is two times y squared.
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    [Deleted User][Deleted User] Posts: 735
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    lemoncurd wrote: »
    Out of interest, what is "z" in the following equation?

    z = 4y ÷ 2y

    Is it
    a) 2
    or
    b) 2y^2

    If you think the answer to the OP is 288, then I presume you would also go for b) here.
    Why? Because, replacing the immediate multipliers with a multiply sign (and I'll use "*" instead of "x"), you have:

    z = 4 * y ÷ 2 * y

    Breaking it down with left-to-right precedence for multiplication and division:

    4 * y ÷ 2 = 2y
    2y * y = 2y^2

    But if you consider "2y" to be an immediate multiplier (and "2(12)" to be the same), then suddenly your answer is different.

    Same answer... 2

    z = 4y ÷ 2y
    z = 2y ÷ y
    z = 2
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    Keiō LineKeiō Line Posts: 12,979
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    CoolboyA wrote: »
    This whole thread just goes to show that maths is not always as "simple" as teachers make out.
    I have never heard anyone make the claim maths is simple.

    In this case we are debating maths notation rather than maths itself
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    LostFoolLostFool Posts: 90,662
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    TheRave wrote: »
    It is bad maths to write such a non-algebraic sum without an operator between the number and the bracket, therefore the result is ambiguous. Please refine the question before answering.

    Best answer so far. The question was posed in very sloppy notation. In "grown up" maths the "÷" sign is rarely used anyway.
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    lemoncurdlemoncurd Posts: 57,778
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    John259 wrote: »
    The spaces are potentially confusing and could be wrongly taken to imply brackets around the 2y, so let's write it as
    4y÷2*y
    which is two times y squared.

    Spaces imply absolutely nothing in algebraic equations (as long as there is an operator on at least one side of a space).
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    [Deleted User][Deleted User] Posts: 735
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    Best answers so far :D
    ? = 48 ÷ 2(9+3)
    ? = 48 ÷ 2(12)
    ? x 2(12) = 48
    ? x 24 = 48
    ? = 48 ÷ 24
    ? = 2
    Same answer... 2

    z = 4y ÷ 2y
    z = 2y ÷ y
    z = 2
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    John259John259 Posts: 28,474
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    Same answer... 2

    z = 4y ÷ 2y
    z = 2y ÷ y
    z = 2
    No. Perhaps you're seeing brackets round the 2y which aren't there, probably because of the spaces.
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    John259John259 Posts: 28,474
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    lemoncurd wrote: »
    Spaces imply absolutely nothing in algebraic equations
    Agreed 100%.
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