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Activity Discussion Math Factorization on cubes in 3 variables

  • Factorization on cubes in 3 variables

    Posted by dontask on December 2, 2023 at 11:49 am

    What is x^3+y^3+z^3 equal to if x+y+z = 0

    Prove that x^3+y^3+z^3 – 3xyz = (x+y+z)(x^2+y^2+z^2-xy-yz-zx)

    Harshwardhan replied 5 months ago 2 Members · 1 Reply
  • 1 Reply
  • Harshwardhan

    Member
    December 15, 2023 at 2:30 pm
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    ::

    The equation in the image is:

    We are also given that:

    We can use the given equation to solve for the value of c3 + y3 + z3.

    One way to solve for + y3 + z3 is to use the factorization:

    3 (c + y + -f- -F z2 — cy — zz — yz)

    We can see that the first term on the right-hand side of this equation is equal to O, since we are given that c + y +z O. Therefore, we have:

    -F y3 -F z3 = O = (c -F y -F -F Y2 -F z2 — cy — cz — yz)

    This means that either c + y + z = O or c2 + Y2 + z2 — cy — cz — yz O.

    If c + y + z = O, then we have already shown that c3 + y3 + z3 O.

    If æ2 + Y2 + z2 — cy — cz — yz 0, then we can rearrange this equation to get:

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