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complex numbers question ?

Been trying to work out this further maths question on complex numbers- it seems ok up to a point but then the markscheme gets really confusing and I cannot work out what they've done. I'd really appreciate it if someone can help me decipher it.

I get to (e^ix (e^2inx -1))/ (e^2ix -1) and this is on the marksheme immediately equated to (e^nix) sin(nx) / sinx

Am I missing something obvious??

Reply 1

Original post
by anonymous_dude
Been trying to work out this further maths question on complex numbers- it seems ok up to a point but then the markscheme gets really confusing and I cannot work out what they've done. I'd really appreciate it if someone can help me decipher it.
I get to (e^ix (e^2inx -1))/ (e^2ix -1) and this is on the marksheme immediately equated to (e^nix) sin(nx) / sinx
Am I missing something obvious??

"Centre" the numeator and denominator, by pulling out a factor like
(e^(i2x) - 1) = e^(ix) (e^(ix) - e*(-ix))
then the map to sin should be straightforward for each.

Reply 2

Original post
by mqb2766
"Centre" the numeator and denominator, by pulling out a factor like
(e^(i2x) - 1) = e^(ix) (e^(ix) - e*(-ix))
then the map to sin should be straightforward for each.


Ah I understand now. Thank you so much for your help :smile:

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