text: # partial fractions
  
  • Sep 12th 2009, 02:45 PM
  helloworld101
  partial fractions
  hi all
  
  am getting trouble expressing the following as a partial fraction. Can u assit me in solving it please.
  
  5x - x^2
  ____________
  x(x-1)(2x+1)
  • Sep 12th 2009, 02:56 PM
  pickslides
  Consider this
  
  $\frac{5x-x^2}{x(x-1)(x-2)} =\frac{A}{x} +\frac{B}{x-1} +\frac{C}{x-2}$
  
  $5x-x^2 =A(x-1)(x-2) +B(x-2)x +C(x-1)x$
  
  now choose values for x to solve for $A,B$ and $C$.
  
  (Rock)
  • Sep 12th 2009, 03:08 PM
  helloworld101
  how did u get (x-2)
  • Sep 12th 2009, 03:16 PM
  mr fantastic
  Quote:
  
  Originally Posted by helloworld101
  how did u get (x-2)
  
  It was a typo but the suggestion on what to do is still completely valid (all you have to do is make the required trivial correction and then continue).
  • Sep 12th 2009, 03:16 PM
  pickslides
  Oops!
  
  Must have had $x-2$ on the mind. Just use my first post and replace $x-2$ with $2x+1$ and you'll be back on track.
  
  Does that help?
  • Sep 12th 2009, 03:35 PM
  helloworld101
  thanks got the answer in the back of the book now...