Proof of the Cofactor Expansion Theorem

Поділитися
Вставка
  • Опубліковано 1 жов 2024

КОМЕНТАРІ • 14

  • @jeffaugust8249
    @jeffaugust8249 Рік тому +1

    Not bad, I understood all of it. I've seen different proofs that expect the reader to assume things, but yours contains only elementary elements that are not complicated.

  • @danielngmoen3901
    @danielngmoen3901 3 роки тому +3

    great video! Greetings from Norway :)

  • @danuso5172
    @danuso5172 4 місяці тому

    Where can I find the definition of elementary matrix?

    • @bvanpelt8
      @bvanpelt8  4 місяці тому

      The definition of an elementary matrix is a square matrix that has exactly one row operation done to it. Check out the following video.
      ua-cam.com/video/7H3JFH3IjB0/v-deo.html&ab_channel=Mathispower4u

  • @skinnykevin3998
    @skinnykevin3998 2 роки тому +1

    Great video! I just had a question, at 23:54 when you expanded the determinant of B on column 1, where exactly did that expansion come from? Is that just something we're assuming to be true?

    • @bvanpelt8
      @bvanpelt8  2 роки тому

      Yeah, in this video I assume the definition of the determinant along the first column.

    • @nguyenjohn1649
      @nguyenjohn1649 2 роки тому

      Yah, the same question with you. It's really confusing. Hopely he will explain it more clearly.

    • @bvanpelt8
      @bvanpelt8  Рік тому

      @@nguyenjohn1649 At the very beginning of the video is the definition that I am working with.

  • @pawekopytek7596
    @pawekopytek7596 2 роки тому

    Question: where did that i + 1 come from at 23:58?
    Edit: I mean apart from the fact that it comes from the general formula which says i + j and j happens to = 1.

    • @bvanpelt8
      @bvanpelt8  2 роки тому

      The definition of the determinant that I am using has that formula as a definition. It's from that definition that I am trying to get to the i + j formula.

  • @toby2582
    @toby2582 11 місяців тому

    15:00 In previous video, You use cofactor expansion on any rows to prove that the swap operation get negative det(A), but in this video, you use this Theorem to prove cofactor expansion along any rows. It feels like an egg and a chicken problem😢

    • @toby2582
      @toby2582 11 місяців тому

      How do I fully know how to prove this theorem properly😢😢😢😢

    • @bvanpelt8
      @bvanpelt8  11 місяців тому

      This video is independent of my other Linear Algebra videos. In fact, I don't require it of my students. I simply put it out as a complete video all its own.
      So, do not use the definition I used in previous videos. In this video, the definition of the determinant was defined to be along the first column. Thus, when I try to prove the theorem along any column, you can roll the columns until you get to the first one, and then you can use the theorem.
      Once again, DO NOT USE any other video of mine - this video is completely self-contained.