What is the Taylor series expansion at ##a/2## for finding real functions?

In summary, the problem asks to find the real functions f such that f'(x) + f(a-x) = e^x, where a is a constant. One possible solution is to use the Abel Identity to eliminate references to f(a-x) and its derivatives, leaving only references to f(x) and its derivatives. Another possible approach is to expand the solution in a Taylor series at the point a/2.
  • #1
L Navarro H
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0
Homework Statement
Find the real functions f so: f' (x) + f (a - x) = e^x
a is a constant
Relevant Equations
none
Mod note: Member warned that some effort must be shown.
 
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  • #2
L Navarro H said:
Homework Statement:: Find the real functions f so: f' (x) + f (a - x) = e^x
a is a constant
Relevant Equations:: none

.
Please post your attempt, per forum rules.
 
  • #3
haruspex said:
Please post your attempt, per forum rules.

I use the Abel Identity to find the functions, but I'm no sure if it's correct to used it in this problem
my answer is {e^x , - 1/(3*e^(2x))
 
  • #4
L Navarro H said:
I use the Abel Identity to find the functions, but I'm no sure if it's correct to used it in this problem
my answer is {e^x , - 1/(3*e^(2x))
Are you saying that each of those is a solution to the equation? Doesn’t look that way to me. Shouldn't 'a' figure in the answer?
Please post your working.

Hint: you need a strategy for eliminating references to f(a-x) and its derivatives so that all the references to f are to f(x) and its derivatives.

Btw, sorry for the delay.. for some reason I did not get the alert. Happens sometimes.

Still there @L Navarro H ? If you need a stronger hint, try two things...
1. Write the equation swapping x and a-x.
2. Differentiate the equation.
Can you see how get rid of references to f(a-x)?
 
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  • #5
have you tried to expand a solution in the Taylor series at the point ##a/2##? That is to look for solutions in the form ##f(x)=\sum_{k=0}^\infty f_k(x-a/2)^k##

upd: but haruspex's idea is better
 
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1. What is a Taylor series expansion?

A Taylor series expansion is a mathematical tool used to approximate a function using a polynomial. It is based on the idea that any function can be approximated by a polynomial with an infinite number of terms.

2. How is a Taylor series expansion calculated?

A Taylor series expansion is calculated by taking the derivatives of a function at a specific point, usually denoted by "a," and plugging these values into a formula that involves powers of the variable "x." The resulting polynomial is the Taylor series expansion of the function at that point.

3. What is the significance of expanding a function using a Taylor series?

Expanding a function using a Taylor series allows us to approximate the value of the function at any point, even if it is not explicitly defined. It also allows us to easily calculate the derivatives of the function at that point.

4. What is the purpose of finding the Taylor series expansion at a/2 specifically?

Expanding a function at a/2 allows us to approximate the function at a point that is closer to the center of the series, which can result in a more accurate approximation. It also allows us to use the properties of even and odd functions to simplify the calculation.

5. Are there any limitations to using a Taylor series expansion to approximate a function?

Yes, there are limitations to using a Taylor series expansion. The series may only converge for certain values of x, so it may not be accurate for all values. Additionally, the accuracy of the approximation depends on the number of terms used in the expansion, so it may not be an exact representation of the function.

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