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A^n/m = Incorrect answer

  1. Jan 22, 2007 #1

    disregardthat

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    My teacher gave us some rules about numbers in the power of brackets.

    Like 2^1/2

    It was: a^1/n= n'root'a

    (instead of a square root (2'root') or cube root (3'root') it was n'root'.)

    Anyway, that equation is correct, at least with the brackets i tryed it with. But when we get numbers that isn't "1/n", but "n/m" he gives us this equation:

    a^n/m = (a^1/m)^n = (m'root'a)^n

    This equation I can't make correct. For example: I do 2^3/2 on my calc, and it gives me this: "4"

    I put it in the equation:

    2^3/2 = (2^1/2)^3

    When I write this new setup on my calc it gives me this: "1"

    I put it in the other equation and do it on my calc:

    2^3/2 = (2'root'2)^3

    It gives me this: "2.8284..."

    There are four possibilities:
    - I must be doing it wrong
    - The equation is incorrect
    - My calc is broke
    - The laws of mathematics have changed

    I am terribly sorry for my topic, I just found out that I forgot to put the bracket power into these: ( )
    :uhh: :uhh: I just leave it standing so it wont be spam until one of the mods deletes it... :frown:
     
    Last edited: Jan 22, 2007
  2. jcsd
  3. Jan 22, 2007 #2

    matt grime

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    You are misusing the calculator

    The third option is the correct answer.

    The errors seem to be that you

    1. cubed 2 to get 8 then divided 8 by 2 to get 4
    2. You actually multiplied 2 by 1/2, rather than raising it to the power 1/2m, to get 1, then cubed 1.
     
  4. Jan 22, 2007 #3

    disregardthat

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    yeah, I forgot the ('s...

    So I raised the number to the power of 1 and then divided it by 2....
    2^1/2
    It really should stay like this: 2^(1/2)

    When I do this it gets correct on my calc, sorry again...
     
  5. Jan 22, 2007 #4

    HallsofIvy

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    Brackets? Don't you mean just fractions?

     
  6. Jan 22, 2007 #5

    disregardthat

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    Sorry, wrong word there, Indeed i meant "fractions" and not "brackets", or parantheses was it, is there any other kind of brackets? I didn't know.

    Hehe, the last one was a joke :)
     
  7. Jan 22, 2007 #6
    Do you still need help specifically with any of the mathematics or was it simply a calculator issue?
     
  8. Jan 22, 2007 #7

    disregardthat

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    I don't need help, thank you :)
     
  9. Jan 22, 2007 #8

    HallsofIvy

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    Just remember- there is no such thing as too many parentheses!
     
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