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**musicmental85** Hi guys,

Still revising for exams! Looking at the following, any help would be appreciated!

Consider the function f_i=PC(2PI), i=1,2

f_1(x)=x f_2(x)=x^2 for 0<=x<2PI

Show that f_1(x) ~ PI- 2 SUM [(sin(nx))/n] (n=1 to oo)

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Given that the function is on (-PI,PI] and is 2PI periodic

Calculate the Fourier Series

xcosx~-(sinx)/2 + 2 SUM [((-1)^k)(k/((k^2)-1)]sin kx (k=2 to oo)

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For the first I think I should be working from the fact that

x~2 SUM [(-1)^(n-1).(Sin nx)/n for -PI<x<PI

but I could be wrong?

It gives almost the same but I'm not sure how or what the differences are.