Results 1 to 3 of 3

Math Help - Please check my complex numbers (Work Included)

  1. #1
    Member
    Joined
    Aug 2009
    Posts
    113

    Please check my complex numbers (Work Included)

    Please check the following complex numbers and let me know if they are correct. If they are not, please point out the mistake/s I am making and what to fix You will be thanked!



    Express in simplest form, in terms of i.

    5. SQRT(-243)


    SQRT(-243) = SQRT(81*3*(-1)) = SQRT(81)SQRT(3)SQRT(-1) = 9SQRT(3i)


    6. 2[SQRT(-81)] - 2[SQRT(-100)]

    2(9i) -2[SQRT(-100)]
    2(9i) -2(10i)
    18i - 20i
    -2i


    7. (2i - 5)/(i + 1)

    -5 + 2i/i + 1
    -5 + 2i/ 1 + i
    -5 + 2i/ 1 + i * 1 - i/1 - i
    (-5 + 2i)(1 - i)/2
    - 3 + 7i/2

    Thanks!!!!!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Banned
    Joined
    May 2009
    Posts
    471
    Quote Originally Posted by bobbyboy1111 View Post
    Please check the following complex numbers and let me know if they are correct. If they are not, please point out the mistake/s I am making and what to fix You will be thanked!



    Express in simplest form, in terms of i.

    5. SQRT(-243)


    SQRT(-243) = SQRT(81*3*(-1)) = SQRT(81)SQRT(3)SQRT(-1) = 9SQRT(3i)


    6. 2[SQRT(-81)] - 2[SQRT(-100)]

    2(9i) -2[SQRT(-100)]
    2(9i) -2(10i)
    18i - 20i
    -2i


    7. (2i - 5)/(i + 1)

    -5 + 2i/i + 1
    -5 + 2i/ 1 + i
    -5 + 2i/ 1 + i * 1 - i/1 - i
    (-5 + 2i)(1 - i)/2
    - 3 + 7i/2

    Thanks!!!!!
    SQRT(-243) = SQRT(81*3*(-1)) = SQRT(81)SQRT(3)SQRT(-1) = 9SQRT(3i) is incorrect, the i doesn't belong under the root

    \sqrt{-243}=\sqrt{81*3*-1}=\sqrt{81}\sqrt{3}\sqrt{-1}=9i\sqrt{3}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Aug 2009
    Posts
    113
    Thanks! So, the rest of my problems are correct?

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Z transform help (work included, maybe property help)
    Posted in the Discrete Math Forum
    Replies: 0
    Last Post: October 9th 2011, 10:57 AM
  2. cos(SQRT{x}) dx (some work included).
    Posted in the Calculus Forum
    Replies: 5
    Last Post: January 15th 2011, 09:41 AM
  3. Replies: 3
    Last Post: January 3rd 2010, 04:07 AM
  4. Replies: 8
    Last Post: March 26th 2009, 02:55 AM
  5. urgent* binomial series help(work included)
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 7th 2007, 05:46 AM

Search Tags


/mathhelpforum @mathhelpforum