Partial Fraction Decomposition

AI Thread Summary
The discussion focuses on finding the partial fraction decomposition of the expression 1/((x^2-1)^2). The user is struggling to determine the values of A and C after reaching a true statement in their calculations. They are advised to solve different simultaneous equations to avoid eliminating A and C prematurely. The suggestion emphasizes the importance of selecting equations that provide distinct information about the variables. This approach aims to clarify the decomposition process and resolve the user's confusion.
opus
Gold Member
Messages
717
Reaction score
131

Homework Statement


Find the partial fraction decomposition for:

##\frac{1}{\left(x^2-1\right)^2}##

Homework Equations

The Attempt at a Solution


Please see my attached images. I think the image shows my thought process better and it would take me well over an hour to type all that out!

Im stuck at the very end, where it results in a true statement, yet I'm trying to get values for A and C (Step iv-c)
 
  • Like
Likes Delta2
Physics news on Phys.org
Please see attached. The second image is Page 1.
 

Attachments

  • 0958D8E0-A450-4049-88FD-4F08FBA8B3E5.jpeg
    0958D8E0-A450-4049-88FD-4F08FBA8B3E5.jpeg
    11.2 KB · Views: 435
  • EDF5BF1D-73D9-46AF-8129-6A82AAC8CCDA.jpeg
    EDF5BF1D-73D9-46AF-8129-6A82AAC8CCDA.jpeg
    32 KB · Views: 454
Try solving the simultaneous equations
## -A - 2B - C + 2D = 0##
## A + B - C + D = 1 ##
instead of the two you choose.

If you add the two equations you choose, you can see that ##A## and ##C## are eliminated from the result, which suggests the two you selected don't provide information about the individual values of ##A## and ##C##.
 
  • Like
Likes Delta2 and opus
Great thank you!
 
  • Like
Likes Delta2
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks

Similar threads

Replies
14
Views
3K
Replies
4
Views
2K
Replies
10
Views
2K
Replies
3
Views
2K
Replies
14
Views
3K
Replies
6
Views
2K
Replies
4
Views
2K
Replies
8
Views
2K
Back
Top