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!

How to simplify

  1. Oct 27, 2013 #1
    I am currently stumped with a mental blackout, how do you simplify this again?

    (-192x^2(4x-3)-4(27-64x^3))/(4x-3)^2

    Wolfram Alpha spits out -32x-12, but how do you get there? :(
     
  2. jcsd
  3. Oct 27, 2013 #2

    rock.freak667

    User Avatar
    Homework Helper

    Expand out each bracket first and then simplify the terms with x's in them.

    2(x+1) = 2x+2

    x^3 +x^2 +2x^3 + 2x^2 = 3x^3 + 3x^2

    After doing that, try to factor out (4x-3)
     
  4. Oct 27, 2013 #3
    Now I have (-512x^3-576x^2-108)/(16x^2-24x+9), but how do I proceed?
    I don't see how I can factor out (4x-3) out of this :/
     
  5. Oct 27, 2013 #4
    Hi, try using synthetic or long division
     
  6. Oct 27, 2013 #5
    There must be an easier way, right? Oo

    Since I got this from having to find the derivative of y=(27-64x^3)/(4x-3) and this is one of the basic problems in my text book. I'm quite sure it doesn't involve long division oO
     
  7. Oct 27, 2013 #6

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Well, you are the one that wanted to know how WA got its answer.

    I think if you re-examine the numerator in you original expression, the term (27 - 64x^3) is the difference of two cubes. If you break this term into its factors, and then check for cancellations, it might be easier than expanding everything at first.
     
  8. Oct 28, 2013 #7
    Got it, thank you...
    Fresh day, fresh mind

    So simply make a polynomial devision BEFORE deriving... But how can I know that beforehand? :/
     
  9. Oct 28, 2013 #8

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    That's what the experience of doing a lot of math problems gives you.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: How to simplify
  1. How to simplify x-x-x (Replies: 4)

Loading...