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KonradZuse

  • 2 years ago

Do there exist scalars k and l such that the vectors u = (2,k,6) , v = (l,5,3) , and w = (1,2,3) are mutually orthogonal with respect to the Euclidean inner product?

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  1. KonradZuse
    • 2 years ago
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    The answer says no, but I originally thought that since k and l were u2 and v1 that itonly matters the 3rd spot, but I realized that you do (u1v1w1) +etc....

  2. KonradZuse
    • 2 years ago
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    Isn't it possible that we could find something = 0? Since that is what orthagonal means.

  3. KonradZuse
    • 2 years ago
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    Oh weait can scalars be negative?

  4. joemath314159
    • 2 years ago
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    if all three vectors were orthogonal, then:\[u\cdot w = 0\Longrightarrow (2)(1)+(k)(2)+(6)(3)=0\]\[2+2k+18=0\Longrightarrow 2k=-20\Longrightarrow k=-10\]Similarly,since v and w are orthogonal, we get that l must be -19.

  5. joemath314159
    • 2 years ago
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    yes scalars can be negative.

  6. KonradZuse
    • 2 years ago
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    So we are actually solving for them...? I thought it was any number..

  7. KonradZuse
    • 2 years ago
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    or those would be the numbers to = 0?

  8. joemath314159
    • 2 years ago
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    Since we are asking "does there exist", the question is asking "is there any one such number k and l." Its not the same as "for all/any k and l."

  9. KonradZuse
    • 2 years ago
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    It doens't say 1 though? Or does that "mutually orthagonal" mean something?

  10. KonradZuse
    • 2 years ago
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    Do there exist scalars k and l such that the vectors

  11. joemath314159
    • 2 years ago
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    If u and w are orthogonal, then k would have to be -10. If k is any other number, they wont be orthogonal since the inner/dot product wouldnt come out to zero.

  12. joemath314159
    • 2 years ago
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    mutually orthogonal means that all three vectors are perpendicular to each other.

  13. joemath314159
    • 2 years ago
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    The thing is, there is no way these three vectors can be mutually orthogonal. Since k would have to be -10, and l would have to be -19. Then u and v wouldnt be orhtogonal. There is no way to get all three to be perpendicular at the same time.

  14. KonradZuse
    • 2 years ago
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    I see, makes sense, thanks!

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