1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Early Linear Algebra

  1. Sep 12, 2006 #1
    I've taken about 3 year break from this style of math, I've been doing Calculus since then. I am taking a begining linear algebra course and I have a system I have to solve with Gaussian Elimination. I know how to work towards a solution and what Gaussian Elimination is. However when I look at this one I just can not see how to start it up.

    Oh yea, the system is:
    x + 2y - z = 4
    y - z = 3
    x + 3y =2z = 7
    2u + 4w + x +7y = 7

    Also if someone on here would be able to post the code for how to get Latex to display it is an augmented matrix I'd be really greatful.

    I feel with this I just need a kick in the right direction.

    Last edited: Sep 12, 2006
  2. jcsd
  3. Sep 12, 2006 #2


    User Avatar
    Science Advisor

    Pick a pivot. In this it looks like a good choice is x in the x + 2y - z = 4. Then eliminate all other variables in that position. The other rows containing an x are x + 3y + 2z = 7 and 2u + 4w + x + 7y = 7.

    It would be easier to do if you had it in a matrix so that the variables are all in order, from x to z.
  4. Sep 12, 2006 #3
    i found this latex code for a matrix:

    [tex ]V = \left( \begin{array}{ccc}1-\frac{1}{2}\lambda^2 & \lambda & A\lambda^3(\rho-i\eta) \\-\lambda & 1-\frac{1}{2}\lambda^2 & A\lambda^2 \\A\lambda^3(1-\rho-i\eta) & -A\lambda^2 & 1\end{array} \right)[/tex]

    which produces this

    [tex]V = \left( \begin{array}{ccc}1-\frac{1}{2}\lambda^2 & \lambda & A\lambda^3(\rho-i\eta) \\-\lambda & 1-\frac{1}{2}\lambda^2 & A\lambda^2 \\A\lambda^3(1-\rho-i\eta) & -A\lambda^2 & 1\end{array} \right)[/tex]

    it's not augmented but i think it still works. it's not necessary to augment your matrices but it might help to remember where the numbers are on one side of the equations. i don't like to augment my matrices because i always forget that there are numbers over there & then i don't do the operations on them.

    as orthodentist said, the first thing you've got to do is pick a pivot. i would go with one that has 1 as its coefficient because it saves a lot of work. it's easier to multiply things by multiples of 1 than some other number or a fraction. then you've got to decide what order you want the other variables in. & you've got to make sure all the equations are written with them in the same order. & don't forget that the coefficient of a certain variable is 0 when it doesn't appear in an equation!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Early Linear Algebra
  1. Linear algebra (Replies: 3)

  2. Linear Algebra (Replies: 5)

  3. Linear Algebra (Replies: 1)