Complex number and power series

rainwyz0706
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Homework Statement



Let ω be the complex number e^(2πi/3), Find the power series for e^z + e^(ωz) + e^((ω^2) z).




Homework Equations





The Attempt at a Solution


I can show that 1+w+w^2=0, don't know if it would help. Could anyone please give me some hints? Any input is appreciated!
 
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Write out the three individual power series and sum them. Collect like powers of z. Use your equation for w to try and simplify the coefficients.
 
I can write it as the sum of (z^n)*(1+w^n+w^2n)/n!, n from 0 to infinity. But I'm still not sure how to simplify 1+w^n+w^2n from 1+w+w^2=0. Could you explain it in a bit more details? Thanks a lot!
 
rainwyz0706 said:
I can write it as the sum of (z^n)*(1+w^n+w^2n)/n!, n from 0 to infinity. But I'm still not sure how to simplify 1+w^n+w^2n from 1+w+w^2=0. Could you explain it in a bit more details? Thanks a lot!

Look at the n=0,1,2,3 cases. Hint, what's w^3? Once you've got those you should find it pretty easy to generalize.
 
thanks, I got it!
 
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