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X+3/3, when x=3

  1. May 19, 2009 #1
    On my assesment it had a question that said x+3/3, when x=3. I thought you do 3/3 first so did the teacher, but when he looke at the answer key it showed you were suppose to do 3+3 then divide by 3. And also on my test booklet, it doesn't have 4 which is the answer if you do it with PEMDAS. Instead they have 2, the answer you get when you add first... :?: Isn't that weird? The same thing happened on my state test. On one of the sample answers the state test gives a question just like that and when my teacher and the student found out the answer on the answer key, the answer only works if you add the two number then divide. And also the state test doesn't offer you the answer you'll get when you do it with PEMDAS. Who's right and who's wrong and what is the correct way to do this? :|
     
  2. jcsd
  3. May 19, 2009 #2

    CRGreathouse

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    Re: Pemdas

    Division always happens before addition unless parentheses change the order. If they want addition first it should be written
    (x+3)/3
    or
    [tex]\frac{x+3}{3}.[/tex]

    I'm not entirely sure I like the abbreviation PEMDAS, though. The order is
    P
    E
    MD
    AS
    which could easily be forgotten in that form.
     
  4. May 20, 2009 #3
    Re: Pemdas

    The funny thing is on the sample answer it doesn't follow PEMDAS. Do you think the other questions like that will follow PEMDAS? Because when I followed PEMDAS to do the problem, there wasn't a choice for my answer which was 4. :uhh:
     
  5. May 20, 2009 #4

    CRGreathouse

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    Re: Pemdas

    Yes. I think it's more likely that the question was changed but not the answer, then that someone used the wrong order of operations in setting up the question. (This actually happens more than you realize!)
     
  6. May 20, 2009 #5
    Re: Pemdas

    I think I got the hang of this now!
     
  7. May 20, 2009 #6

    Hurkyl

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    Re: Pemdas

    Just checking... that is exactly what the problem said, right? The expression was

    [tex]x + 3 / 3[/tex]

    and it was not

    [tex](x + 3) / 3[/tex]

    and it was not

    [tex]\frac{x+3}{3}[/tex]

    ?
     
  8. May 20, 2009 #7
    Re: Pemdas

    I think the question meant [tex]\frac{x+3}{3}[/tex], instead of [tex]x+\frac{3}{3}[/tex].
     
  9. May 20, 2009 #8
    Re: Pemdas

    If the question meant this [tex]\frac{x+3}{3}[/tex], I would add first then divide?
     
  10. May 20, 2009 #9

    CRGreathouse

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    Re: Pemdas

    Yes.
     
  11. May 20, 2009 #10
    Re: Pemdas

    i think that unless the assessment is to test PEMDAS (first time i heard of that actually), then giving something like x+3/3 is just lazy. however, if i was given that, i would have assumed it meant (x+3)/3. no reason why someone would actually put 3/3 in an equation unless the intention was to trick.
     
  12. May 20, 2009 #11
    Re: Pemdas

    Thanks for the help! :)
     
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