Solving Bessel Functions Homework Questions

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SUMMARY

This discussion focuses on solving homework problems related to Bessel functions, specifically the first kind, denoted as ##J_1(x)## and ##J_0(x)##. The first problem involves differentiating the expression ##xJ_1(x) - \int_0^x tJ_0(t) dt##, which simplifies to zero. The second problem raises questions about handling the integral of ##J_n(x)##, while the third problem seeks to determine coefficients ##c_k## for the series involving the zeros of ##J_0##. Participants express varying levels of understanding, particularly in the context of Bessel function theory.

PREREQUISITES
  • Understanding of Bessel functions, particularly ##J_0(x)## and ##J_1(x)##.
  • Knowledge of calculus, specifically differentiation and integration techniques.
  • Familiarity with infinite series and convergence concepts.
  • Basic understanding of mathematical notation and functions.
NEXT STEPS
  • Study the properties and applications of Bessel functions, focusing on ##J_n(x)##.
  • Learn techniques for evaluating integrals involving Bessel functions.
  • Explore the concept of zeros of Bessel functions and their significance in mathematical physics.
  • Investigate series expansions and convergence criteria for infinite series.
USEFUL FOR

Students studying applied mathematics, particularly those tackling problems involving Bessel functions and their applications in physics and engineering.

skrat
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Homework Statement


Calculate:
a) ##\frac{d}{dx}(xJ_1(x)-\int _0^xtJ_0(t)dt)##
b) ##xJ_1(x)-\int _0^xtJ_0(t)dt##
c) let ##\xi _{k0} ## be the ##k## zero of a function ##J_0##. Determine ##c_k## so that ##1=\sum _{k=1}^{\infty }c_kJ_0(\frac{x\xi _{k0}}{2})##.

Homework Equations


The Attempt at a Solution



a) ##\frac{d}{dx}(xJ_1(x)-\int _0^xtJ_0(t)dt)=xJ_0(x)-xJ_0(x)=0##.

b) What do I do with the integral? Should I calculate ##J_n(x)=\frac{1}{\pi }\int _0^{\pi }cos(tsin\varphi -n\varphi)d\varphi ## for n=0?

c) Hmmm, no idea here :/
 
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skrat said:

Homework Statement


Calculate:
a) ##\frac{d}{dx}(xJ_1(x)-\int _0^xtJ_0(t)dt)##
b) ##xJ_1(x)-\int _0^xtJ_0(t)dt##
c) let ##\xi _{k0} ## be the ##k## zero of a function ##J_0##. Determine ##c_k## so that ##1=\sum _{k=1}^{\infty }c_kJ_0(\frac{x\xi _{k0}}{2})##.


Homework Equations





The Attempt at a Solution



a) ##\frac{d}{dx}(xJ_1(x)-\int _0^xtJ_0(t)dt)=xJ_0(x)-xJ_0(x)=0##.

b) What do I do with the integral? Should I calculate ##J_n(x)=\frac{1}{\pi }\int _0^{\pi }cos(tsin\varphi -n\varphi)d\varphi ## for n=0?

c) Hmmm, no idea here :/

I'm no expert in the theory of Bessel functions, but isn't the expression in part b) just the integral of the entire expression in a) wrt x? Integrating 0 gives you a constant. The constant can easily be found by subbing in a suitable value of x, right?

c) exceeds my knowledge, someone else will have to help, sorry.
 

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