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Homework Help: Algbra equation

  1. Feb 24, 2010 #1
    1. The problem statement, all variables and given/known data

    I need help with this euation:

    0,5m^4/5 = 2u^1/5
    u^4/5 m^1/5

    it's been calculated to be:

    0,5m = 2u => m = 4u

    i need the calculations inbetween..

    So far i have come to think that they cross out 4/5, on one side.

    and on the other they have crossed out 1/5.

    and they are left with:

    0,5m = 2u
    u m

    But what now?

    Note: (u) is supposed to be under 0,5m, and (m) is supposed to be under 2u

    Likewise with the one on top of the page.
    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 24, 2010 #2


    Staff: Mentor

    Your equation seems to be
    [tex]\frac{.5m^{4/5}}{u^{4/5}} = \frac{2u^{1/5}}{m^{1/5}}[/tex]

    An obvious thing to do would be to multiply both sides by u4/5m1/5. This is equivalent to what is called cross-multiplying. Don't think of this as "crossing out" anything.

    From the equation above, you get .5m = 2u. Can you take it from there?
  4. Feb 24, 2010 #3
    yeah, you have typed question wrong. or otherwise there is a misprinting in your book either in question or in solution.

    See the answer for your given question
    \frac{0.5m^{4/5}}{u^{4/5}.m^{1/5}} = 2u^{1/5}

    \frac{m^{4/5}}{u^{4/5}.m^{1/5}} = 4u^{1/5}


    m^{3/5} = 4u



    m = (4u)^{5/3}

    Last edited: Feb 25, 2010
  5. Feb 24, 2010 #4
    to snshusat:

    yes, it's supposed to be the way mark wrote.

    how do you write it like that btw?

    to mark:

    okey so then i get 0,5m^4/5*m^1/5 = 2u^1/5*u^4/5

    so: 0,5m^5/5 = 2u^5/5

    and then: 0,5m = 2u

    and then finally: m = 4u

    Last edited: Feb 24, 2010
  6. Feb 24, 2010 #5
  7. Feb 25, 2010 #6


    User Avatar
    Homework Helper

    Even though the question was different, this is incorrect.



    edit: after seeing your latex as {4u}^{5/3} you weren't wrong, but you should have added parentheses around the (4u).
  8. Feb 25, 2010 #7
    thanks for figuring it out, this code is very hard to type.

    Edit: I think I should have used () in place on {}. I thought that I've become so expert in typing those codes that I've not reviewed it again after posting. That guy may have got punishment from his teacher if he had copied that solution. Sorry :(
    Last edited: Feb 25, 2010
  9. Feb 25, 2010 #8


    User Avatar
    Homework Helper

    Sure he would have! You started with the wrong question :tongue:
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