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Easy Algebra Problem :/

  1. Feb 19, 2008 #1
    1. The problem statement, all variables and given/known data

    .4 = [20%]/[x]


    2. Relevant equations



    3. The attempt at a solution

    This is what I tried...but I know this isnt right as I need an actual value for x.

    .4 = (.2)(x^-1)
    .4 / .2 = x^-1
    2 = x^-1
    2 = 1 / x
     
    Last edited: Feb 19, 2008
  2. jcsd
  3. Feb 19, 2008 #2
    You're almost done. multiply both sides by x, then divide by 2.
     
  4. Feb 19, 2008 #3
    2(x) = (1/x)(x)
    2x = 1
    x = 1/2

    Is that right?
     
  5. Feb 19, 2008 #4
  6. Feb 20, 2008 #5
    [tex].4=\frac{.2}{x}[/tex]

    Converting decimals to fractions ...

    [tex].4=\frac{4}{10}=\frac 2 5[/tex]

    [tex].2=\frac{2}{10}=\frac 1 5[/tex]

    Substituting ...

    [tex]\frac 2 5 = \frac{1}{5x}[/tex]
     
  7. Feb 20, 2008 #6
    I dont think that is correct. If I solved Roco's equation I would get:
    2/5 = 1/5x
    (2/5) / (1/5) = x
    2 = x

    When really the solution is .5

    I think you mean by substituting fractions would be...
    2/5 = (1/5) / x

    But thank you for trying to help :D I just dont want someone else to get confused if they look at this later.
     
  8. Feb 20, 2008 #7

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    No you wouldn't, you'd get [tex]\frac{2/5}{1/5}=\frac{1}{x} \Rightarrow x=\frac{1}{2}[/tex]
     
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