[tex]\sum_{n=-\infty}^{\infty}r^{|n|}e^{inx}=[/tex][tex]\sum_{n=1}^{\infty}e^{inx}[/tex]+ [tex]r^{0}e^{0}[/tex] +[tex]\sum_{n=-\infty}^{\infty}r^{n}e^{-inx}[/tex](adsbygoogle = window.adsbygoogle || []).push({});

if we look at the left side

i have been told that it was broken by intervals

the left most is for n=1.. infinity the central is for n=0

the right most for n=-1 ..-infinity

i know the definition of the |x| function

for some values its x for other its -x

but here the power of e changes too

why?

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# Homework Help: Breaking this expressions into areas.

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