Sums of even and odd functions

Click For Summary
SUMMARY

The discussion centers on the decomposition of the function k(x) = (x^2 + 4)/(x + 1) into even and odd components. It is established that there is no interval (-a, a) where k is classified as either even or odd due to the failure of k(x) to satisfy the conditions k(x) = k(-x) and k(x) = -k(-x). Participants suggest using a proof by contradiction for part (i) and recommend analyzing the function t(x) = f(x) - f(-x) for part (ii). The conclusion emphasizes that k(x) cannot equal g(x) + h(x) for all x in the domain of k due to the exclusion of x = -1 from its domain.

PREREQUISITES
  • Understanding of even and odd functions
  • Familiarity with function decomposition
  • Knowledge of proof techniques, specifically proof by contradiction
  • Basic algebraic manipulation of rational functions
NEXT STEPS
  • Study the properties of even and odd functions in depth
  • Learn about function decomposition techniques
  • Explore proof by contradiction with examples
  • Investigate the implications of domain restrictions in rational functions
USEFUL FOR

Mathematics students, educators, and anyone studying function analysis and decomposition techniques in calculus or algebra.

Charismaztex
Messages
45
Reaction score
0

Homework Statement



If f:(-a,a)-->Real numbers, then f can be rewritten as the sums of an even and an odd function

Let k: Real numbers\{-1}-->Real numbers be given by k(x)=\frac{x^2+4}{x+1}

(i) Prove that there is no interval (-a,a) on which k is either even or odd
(ii) Find an even function g, an odd function h and a value a for which
k(x)= g(x) +h(x), x belongs to (-a,a)
(iii) Explain why it is, or is not, true that k(x)=g(x) +h(x) for all x in the domain of k


Homework Equations



N/A

The Attempt at a Solution



(i) Is it true that by proving k(x) does not equal k(-x) and k(x) does not equal -f(-x), we can prove that there is no interval (-a,a) on which k is either even or odd?

(ii) I am not quite sure here.

(iii) is it not true because x cannot be -1?

Thanks in advance,
Charismaztex
 
Physics news on Phys.org
For i) use a proof by contradiction. Assume there is an interval (-a,a) on which k is either even or odd, then on some subset of that, say [-b,b], it must be either even or odd as well.

ii) Study t(x)= f(x) - f(-x)

iii) Give it another look once you find g(x) and h(x). In response to your original attempt, I suggest you read the question again carefully. Whilst it is true that x can not be -1, -1 is not in the domain of k. Good luck
 

Similar threads

  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
7
Views
4K
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K