1. Not finding help here? Sign up for a free 30min 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!

Simple Factoring Problem

  1. Feb 20, 2007 #1
    1. The problem statement, all variables and given/known data

    [tex]28s^2 + 8st - 20t^2[/tex]

    The answer in the back of the book is 4(7s - 5t)(s + t)

    2. The attempt at a solution

    [tex]4(7s^2 + st + st - 5t^2)[/tex]
    [tex]4(7s^2 + st + st - 20t^2)[/tex]
    [tex]4(s(7s + t) + t(s - 20t))[/tex]

    I'm lost, can someone please help me?

    Thanks in advance.
     
    Last edited: Feb 20, 2007
  2. jcsd
  3. Feb 20, 2007 #2
    In your first attempt at the solution, why not combine the second and third terms inside the (), it might make things more obvious.
     
  4. Feb 20, 2007 #3
    Is there some trick to this that I am missing?

    [tex]4(7s^2 + 2st - 5t^2)[/tex]
     
  5. Feb 20, 2007 #4

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Well, you could note that 2st=7st-5st, which makes your expression 4(7s2+7st-5st-5t2). Is this any easier to factorise?
     
  6. Feb 20, 2007 #5
    OHH OHH OHHHH OHHHHHH!!!

    Oh my god, how could I be so blind? That t^2 at the end threw me off. I feel like such an idiot. Thanks a billion cristo and robb, and I apologize for wasting your time :)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Simple Factoring Problem
  1. Factoring problem (Replies: 5)

  2. Factoring problem (Replies: 3)

  3. Factoring problem (Replies: 11)

Loading...