Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Math help

  1. Feb 12, 2005 #1
    [tex]3y^{\frac{2}{3}}=x[/tex]
    How do I make y the subject?
    [tex]y^{\frac{2}{3}}=\frac{x}{3}[/tex]
    Then what?
     
  2. jcsd
  3. Feb 12, 2005 #2

    VietDao29

    User Avatar
    Homework Helper

    Hi,
    y >= 0
    Then
    [tex]y = \sqrt[\frac{2}{3}]{\frac{x}{3}} = \sqrt{(\frac{x}{3})^{3}} [/tex]
    Hope it help,
    Viet Dao,
     
  4. Feb 12, 2005 #3
    How did you go from [tex]\sqrt[\frac{2}{3}]{\frac{x}{3}}[/tex] to [tex]\sqrt{(\frac{x}{3})^{3}}[/tex]
     
  5. Feb 12, 2005 #4
    Using the law of indicies that says a^mn = (a^m)^n.

    y^(2/3) = x/3

    Cube both sides: y^2 = (x/3)^3

    Now square root both sides: y = (x/3)^3/2 = [(x/3)^3]^1/2, which is what you have (I can't use LaTeX properly, oops).
     
  6. Feb 12, 2005 #5

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    That root in the LHS is another way of writing
    [tex] (\frac{x}{3})^{\frac{3}{2}}=[(\frac{x}{3})^{3}]^{\frac{1}{2}}=\sqrt{(\frac{x}{3})^{3}} [/tex]

    Daniel.
     
  7. Feb 12, 2005 #6
    Oh ya! Forgot about that. :rolleyes:
    Thanks for the help guys!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook