Results 1 to 3 of 3

Math Help - Solving linear equation using matrices Can some please check?!?

  1. #1
    Newbie
    Joined
    Aug 2008
    From
    Near London
    Posts
    19

    Solving linear equation using matrices Can some please check?!?

    Hi could some one please check this work, it's to solve the following system of linear equations using matrices.
    -3x-2y=15
    -9x+8y=3

    As a matrice
    [-3 -2] [x] [15]
    [-9 8] [y] [3]

    Determinant (-3)*8-(-2)*(-9)=-42

    [-8/-42 -2/-42]
    [-9/-42 -3/42]

    [-4/-21 -2/21]
    [-3/14 1/14]

    -4/21*15 + -1/21*3=-3
    -3/14*15 +1/14*3 =-3

    x=-3 y=-3

    Many thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Mar 2007
    Posts
    1,240

    Talking

    You can check the answer to any "solving" problem by plugging it back in to the original exercise. In your case, plug in your values for "x" and "y", and see if they work:

    . . . . .-3[-3] - 2[-3] = 9 + 6 = 15 (yes!)

    . . . . .-9[-3] + 8[-3] = 27 - 24 = 3 (yes!)

    Since your solution values "check", your answer must be correct.

    Good work!

    P.S. Thank you for showing all your work!!
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Aug 2008
    From
    Near London
    Posts
    19
    Praise!!
    many thanks.

    S
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Linear Equation and matrices.
    Posted in the Advanced Algebra Forum
    Replies: 9
    Last Post: October 2nd 2011, 04:31 PM
  2. Solving a system of linear equations using matrices.
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: May 12th 2010, 05:09 AM
  3. linear code,parity check matrices
    Posted in the Discrete Math Forum
    Replies: 0
    Last Post: March 29th 2010, 06:41 PM
  4. Replies: 3
    Last Post: March 8th 2009, 08:15 AM
  5. Replies: 3
    Last Post: March 24th 2008, 07:10 AM

Search Tags


/mathhelpforum @mathhelpforum