Results 1 to 6 of 6
Like Tree5Thanks
  • 1 Post By MaxJasper
  • 1 Post By a tutor
  • 1 Post By Soroban
  • 1 Post By SworD
  • 1 Post By Prove It

Math Help - Decimal powers

  1. #1
    Newbie
    Joined
    Sep 2012
    From
    uk
    Posts
    3

    Decimal powers

    just curious to know if its ok to write powers of a number as decimals or if they have to be fractions in order to be marked as correct in an exam.

    e.g. a^1/2 * a^2

    is it correct to write the answer as a^2.5 or does it have to be a^5/2 in an exam.

    (the answer in the back of the book was a^5/2 but id like to know if it would still be marked correct in an exam if you wrote it as a^2.5)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member MaxJasper's Avatar
    Joined
    Aug 2012
    From
    Canada
    Posts
    482
    Thanks
    54

    Re: Decimal powers

    5/2 looks like an exact number while 2.5 leaves doubts of whether it is truncated or not....so on....
    Thanks from ineedmathshelp
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Jan 2008
    From
    UK
    Posts
    484
    Thanks
    66

    Re: Decimal powers

    5/2 = 2.5 so there's no problem. However fractions are often easier to work with.
    Thanks from ineedmathshelp
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,806
    Thanks
    697

    Re: Decimal powers

    Hello, ineedmathshelp!


    What would you do with \sqrt[3]{x} ?


    The correct form is: . x^{\frac{1}{3}}

    Would you write it as x^{0.3} or x^{0.33} or x^{0.333} ?


    Consider: \sqrt[3]{8}

    The cube root of 8 is 2 . . . right?

    \text{But: }\:\begin{Bmatrix}8^{0.3} &=& 1.8661... \\ 8^{0.33} &=& 1.9862... \\ 8^{0.333} &=& 1.9986... \\ \vdots && \vdots \end{Bmatrix} \quad\text{None of these is correct.}

    Thanks from ineedmathshelp
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Sep 2012
    From
    Planet Earth
    Posts
    196
    Thanks
    49

    Re: Decimal powers

    Yes but Soroban, 4^{0.5} = 2 IS correct. So how can we be sure you HAVE to use fractions even when the exact decimal is available? I don't really know how to answer this, I'd say it depends on the professor/teacher, but maybe there's some kind of notation rule that I'm not aware of or something... Maybe you should use fractions to be safe.
    Last edited by SworD; September 15th 2012 at 08:37 AM.
    Thanks from ineedmathshelp
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,662
    Thanks
    1481

    Re: Decimal powers

    Quote Originally Posted by SworD View Post
    Yes but Soroban, 4^{0.5} = 2 IS correct. So how can we be sure you HAVE to use fractions even when the exact decimal is available? I don't really know how to answer this, I'd say it depends on the professor/teacher, but maybe there's some kind of notation rule that I'm not aware of or something... Maybe you should use fractions to be safe.
    I agree, if you use fractions you can't go wrong.
    Thanks from ineedmathshelp
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. How to mod a decimal
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: October 3rd 2011, 07:19 AM
  2. decimal help
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 2nd 2008, 08:21 AM
  3. i need some help on decimal?anyone???
    Posted in the Algebra Forum
    Replies: 1
    Last Post: July 11th 2008, 08:22 PM
  4. Decimal
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 18th 2007, 01:28 PM
  5. decimal
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 27th 2007, 03:05 PM

Search Tags


/mathhelpforum @mathhelpforum