Algebra 2 help! ?

I’ve been trying to figure out how to solve this bonus question and it doesn’t make sense. I think you solve using diagonals but I’m having trouble with solving 

Attachment image

3 Answers

Relevance
  • nbsale
    Lv 6
    1 month ago

    Since column 1 = column 3, you immediately know that the determinant is 0. You can work it out like others did, and you should know now to do that, but for this particular problem there's no need for that.

    It's always = 0 when the rows or the columns are not linearly independent.

  • 1 month ago

    It's asking for the determinant of a 3x3 matrix.

    Let's assume you had a matrix that was:

    M = [a b c]

    ...... [d e f]

    .......[g h i]

    The determinant would be:

    |M| = a(ei − fh) − b(di − fg) + c(dh − eg)

    That may look complicated, but look at the picture below to see how you get there.

    In your case you have:

    [d f d]

    [1 1 1]

    [f d f]

    That will become:

    d(1f - 1d) + f(1f - 1f) + d(1d - 1f)

    = d(f - d) + 0 + d(d - f)

    = d(f - d) - d(f - d)

    = 0

    Answer:

    0

    Attachment image
  • Alan
    Lv 7
    1 month ago

    since the lines are | |

    it is asking for the determinant

    so for a 3 x 3 is it rather simple

    d ( f -d) - f (f-f) + d ( d-f)

    answer is:

    df -dd + dd -df = 0

    answer is : 0

Still have questions? Get your answers by asking now.