Results 1 to 2 of 2

Math Help - quick complex number qu.

  1. #1
    Member
    Joined
    Apr 2008
    Posts
    85

    quick complex number qu.

    if i want to find the complex number of say:

    |z|=3 rt(7) and Re(z)=0 ....point of intersection

    then id get to y^2= 3 rt(7) and would i take the negative root and just make into a complex number so 3rt(7) i
    ??
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by skystar View Post
    if i want to find the complex number of say:

    |z|=3 rt(7) and Re(z)=0 ....point of intersection

    then id get to y^2= 3 rt(7) and would i take the negative root and just make into a complex number so 3rt(7) i
    ??
    Geometrically it is seen that |z|=3 \sqrt{7} is a circle of radius 3 \sqrt{7} with centre at the origin. Re(z) = 0 is the imaginary axis. Clearly then the points of intersection are (0, 3 \sqrt{7}) and (0, - 3 \sqrt{7}).

    By the way, |iy| = 3 \sqrt{7} \Rightarrow |i| |y| = 3 \sqrt{7} \Rightarrow |y| = 3 \sqrt{7} \Rightarrow y = \pm 3 \sqrt{7}.

    Again, you've misunderstood how to get the magnitude of a complex number.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. quick complex number questions
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: November 7th 2010, 11:21 PM
  2. Replies: 1
    Last Post: October 2nd 2010, 01:54 PM
  3. Replies: 3
    Last Post: September 13th 2010, 11:13 AM
  4. quick complex number question
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: January 8th 2009, 04:08 AM
  5. quick complex number question
    Posted in the Advanced Algebra Forum
    Replies: 6
    Last Post: January 15th 2008, 02:28 PM

Search Tags


/mathhelpforum @mathhelpforum