1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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
    How do I make y the subject?
    Then what?
  2. jcsd
  3. Feb 12, 2005 #2


    User Avatar
    Homework Helper

    y >= 0
    [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


    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]

  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