Find the power series representation for g centered at 0 by differentiating or integrating the power series for f(perhaps more than once).

ka1leE

ka1leE

Answered question

2021-03-07

Find the power series representation for g centered at 0 by differentiating or integrating the power series for f(perhaps more than once). Give the interval of convergence for the resulting series.
g(x)=ln(12x) using f(x)=112x

Answer & Explanation

lobeflepnoumni

lobeflepnoumni

Skilled2021-03-08Added 99 answers

To determine the radius of convergence and derive the power series of g(x) from the power series for f(x)
The geometric series generated from is all that the power series for f(x) is. 11y, setting y=2x. Its convergence radius is 0.5.
Let
f(x)=112x=1+(2x)+(2x)2+...+(2x)n+...
expanded power series (geometric series),
valid for |2x|<1, |x|<0.5
so, radius of convergence =0.5
By term-by-term integrating the power series of f(x), one may find the power series for g(x) (upto a constant). G(dradius )'s of convergence is same to f(x )'s (from general theory) =0.5
Now, g(x)=ln(12x)
=2dx(12x)=2f(x)dx
=2[1+(2x)+(2x)2+...+(2x)n+...]dx
=2x(2x)22(2x)33(2x)44...(2x)nn...
is the radius of convergence for the power series expansion of g(x) =0.5

Jeffrey Jordon

Jeffrey Jordon

Expert2021-12-16Added 2605 answers

Answer is given below (on video)

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