Power Series Representation of xln(1+x^2)

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SUMMARY

The discussion focuses on deriving the power series representation of the function xln(1+x²). The key approach involves recognizing that the power series expansion of ln(1+u) around u=0 can be utilized, where u is substituted with x². The user initially struggled with the integration of derivatives but ultimately clarified that the function can be simplified without the need for double summation. The final representation is achieved by combining the series for x and ln(1+x²).

PREREQUISITES
  • Understanding of power series expansions
  • Familiarity with logarithmic functions, specifically ln(1+u)
  • Basic calculus concepts, including differentiation and integration
  • Knowledge of convergence criteria for series
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  • Study the power series expansion of ln(1+u) in detail
  • Explore techniques for manipulating power series
  • Learn about convergence tests for series
  • Investigate applications of power series in solving differential equations
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Write a power series representation of xln(1+x2)

My first instinct was to attempt to take the second derivative and then find the summation and then integrate but that approach seemed to be a dead end. Basically, the x thrown in there confuses me and you can't split the function into two separate summations since one would not converge. Any hints..?
 
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Help, anyone?
 
I assume you are expanding around x=0. The power series expansion of x is x. What's the power series expansion of ln(1+u) around u=0? Hence what's the power series expansion of ln(1+x^2). There is no double summation to worry about.
 
Dick said:
I assume you are expanding around x=0. The power series expansion of x is x. What's the power series expansion of ln(1+u) around u=0? Hence what's the power series expansion of ln(1+x^2). There is no double summation to worry about.

I really need to put more thought into problems before posting here. Thanks, and I figured it out.
 

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