The Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: complex numbers
Replies: 8   Last Post: Jan 31, 2007 7:33 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
nonton

Posts: 350
Registered: 1/29/05
complex numbers
Posted: Jan 30, 2007 5:21 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

How would i evaluate the following:

1+2w+3w^2+...+nw^n-1, where w is an nth root of unity.

apparently, the solution is: n(n+1)/2 if w= 1

I don't know how they got this? Any hints please?

Also how do i describe a family of curves in the complex plane:

1. Re(1/z)= C

The answer is a family of circles centered at 1/(2C)+0i of radius 1/
modulus 2C but with the origin excluded.

My question is how did they get the center as 1/(2C)+0i and radius 1/
modulus 2C.

I got the Re(1/z)= x/(x^2+y^2) = C but how do i obtain the radius and
the center as indicated above?

I know the equation of a circle is: x^2 +y^2= r^2

Thank you in advance.




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.