Results 1 to 3 of 3

Math Help - Roots

  1. #1
    Newbie
    Joined
    Apr 2008
    Posts
    16

    Roots

    Show that 4+i and -4-i are the sqaure rooots of 15 +8i
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by meli3000 View Post
    Show that 4+i and -4-i are the sqaure rooots of 15 +8i

    It is sufficient to show that

    (4+i)^2=15+8i

    and that:

    (-4-i)^2=15+8i

    to show that 4+i and -4-i are square roots of 15+8i. (In fact it is sufficent to show that one of these is a square root since the other is minus one times it, and so also of necessity a square root of 15+8i)

    RonL
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,708
    Thanks
    1638
    Awards
    1
    Quote Originally Posted by meli3000 View Post
    Show that 4+i and -4-i are the sqaure rooots of 15 +8i
    Do you know how to square a binomial?
    (a+bi)^2=?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. roots
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: December 24th 2010, 02:50 AM
  2. Roots & Imaginary Roots
    Posted in the Math Topics Forum
    Replies: 4
    Last Post: October 4th 2009, 09:24 AM
  3. roots
    Posted in the Advanced Algebra Forum
    Replies: 3
    Last Post: April 29th 2009, 05:27 AM
  4. Roots ><
    Posted in the Algebra Forum
    Replies: 3
    Last Post: October 7th 2008, 08:49 AM
  5. Given 2 imaginary roots find other 2 roots
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: January 26th 2008, 09:24 PM

Search Tags


/mathhelpforum @mathhelpforum