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: I'm drawing a blank please help!

  1. Sep 14, 2006 #1
    Hi, I have calculus 2 in college right now and am drawing a complete blank and need to get my homework done. If I wanted to take the integral of 2/((x^2)-1)...what would I do or where would I start? Thanks!!
     
  2. jcsd
  3. Sep 14, 2006 #2
    Use partial fractions.
     
  4. Sep 14, 2006 #3

    HallsofIvy

    User Avatar
    Science Advisor

    First, that 2 in front shouldn't bother you. Just do the integral without the 2, then multiply by 2.
    [tex]\frac{1}{x^2- 1}= \frac{1}{(x-1)(x+1)}[/tex]
    and that can be expanded by "partial fractions":
    [tex]\frac{1}{x^2-1}= \frac{A}{x-1}+ \frac{B}{x+1}[/tex]
    To find A and B, multiply both sides of that by x2-1 then let x= 1 and -1 in turn.

    To integrate the resulting fractions, look up the integral of [itex]\frac{1}{x}[/itex].
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook