Cube root rationalization - Viewer Submission

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  • Опубліковано 8 січ 2025
  • Submit your math problems to me at mathoutloud40@gmail.com and I'll attempt a solution as I see it for the first time.
    #math #maths #mathematics

КОМЕНТАРІ • 6

  • @slytherinbrian
    @slytherinbrian Місяць тому +2

    That was really impressive. I knew the result would be SOMETHING like that, but I just couldn't work it out.

  • @RajSandhu-gm8iz
    @RajSandhu-gm8iz Місяць тому +1

    Thanks for doing question. It was in a 1960's UK textbook. I was flummoxed by it, I only really knew how do to the square root type questions.
    As you said, in this case the conjuagte to use relies on using the cube relationship a³ -b³ = (a-b)(a² +b² +ab)

  • @dan-florinchereches4892
    @dan-florinchereches4892 Місяць тому +1

    I am curious if you will just use the algebraic identity A^3-B^3=(A-B)(A^2+AB+B^2) . This along with (a+b)^2 , (a-b)^2 , a^2-b^2 and a^3+b^3 were written on the back of the maths "lab" in my secondary school.
    Also in a corner there was a drawing about the itentity 1l=1dm^3 with a 1L jug flowing into a 1dm sided cube

    • @RajSandhu-gm8iz
      @RajSandhu-gm8iz Місяць тому

      Only need to use the identity you first mentioned in this case.

    • @dan-florinchereches4892
      @dan-florinchereches4892 Місяць тому

      Just sharing nice memories of my school
      As a cool fact our school had wooden flooring which was treated with petrol (the kind also used in hair treatment) and the benches came in 1 piece with seats all bolted to the floor.
      When we were sixth and seventh grade we were just big enough to land feet on the edge of the first row of benches and hands on blackboard pretending to be superman

    • @mathoutloud
      @mathoutloud  Місяць тому +1

      I wanted to, but couldn’t remember the exact coefficients. I don’t know if I was just too tired or had some kind of brain block, but essentially I went through the work of rederiving that factorization.