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: Simplifying Inequalities

  1. Feb 9, 2005 #1
    I have an inequality:

    1296(b^3) - 324(b^2) - 1008b + 108 > 0.

    I want to know for what values of b this inequality is true. Any suggestions?
     
  2. jcsd
  3. Feb 9, 2005 #2

    ehild

    User Avatar
    Homework Helper

    I do not think you can simplify the expression too mutch except factoring out 36.

    Anyway, it is a third order polynomial, which goes from -infinity to + infinity, and having either one or three real roots. You can find them approximately(-0.821, 0.105, 0.966). As the polynomial is negative for very low values of b and positive for very high ones, it is positive between the first two roots and also for b higher than the highest root.

    ehild
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook