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: Solving an equation

  1. Nov 19, 2011 #1
    Solve the equation [tex]x^4 - x^2 = k[/tex] where [itex]k>0[/itex].

    Am I being thick or how do I solve this for [itex]x[/itex]?

    Factorising gives [tex]x^2(x^2-1)=k[/tex] but now where?
     
  2. jcsd
  3. Nov 19, 2011 #2

    HallsofIvy

    User Avatar
    Science Advisor

    Let [itex]y= x^2[/itex] and that becomes a quadratic function:
    [itex]y^2- y= k[/itex] or [itex]y^2- y- k= 0[/itex]. Solve that for y, then solve [itex]x^2= y[/itex] for x.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook