General

[quote=gamemage3]rewrite that in terms of cos(x) + isin(x), then in e^ix.

then plug that in for formula of geometric series

i see what you did wrong, you put 80 instead of 81

so 2pi/3 * 81 gives some multiple of 2pi, giving e^0 making the top go to 0.[/quote]

Ohhhh I seeee. Thanks, I see what I did wrong. Should be to the 81st power and not 80 haha.

[quote=Invictinite]if you convert it to polar form, you get z = e^(2pi/3)i[/quote]

Thanks!

if you convert it to polar form, you get z = e^(2pi/3)i

rewrite that in terms of cos(x) + isin(x), then in e^ix.

then plug that in for formula of geometric series

i see what you did wrong, you put 80 instead of 81

so 2pi/3 * 81 gives some multiple of 2pi, giving e^0 making the top go to 0.