A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

nthenic_oftime

  • one year ago

please help.. idk how to even figure this out so steps would be nice too. Find the specified vector or scalar. u = -4i + 1j and v = 4i + 1j; Find . ||u+v|| A. Sqrt34 B. 8 C. 5 D. 2

  • This Question is Closed
  1. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    first add the "corresponding" terms then find the length of the resulting vector (length is sqrt(sum of square of each term))

  2. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    for example the length of 3i+4j is \[ \sqrt{3^2+4^2} = \sqrt{9+16}= \sqrt{25} = 5\]

  3. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    hey thank you for that a answer can you show me how you got got the length of the vector

  4. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    what did you get for u+v?

  5. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    wait i misunderstood i thought that was the same thing. im so confused

  6. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    first add corresponding terms gives us... i+2j ?

  7. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    idk how to find the length of a vector

  8. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    -4i + 1j 4i + 1j

  9. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    -4i + 4i is not i

  10. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    its 0?

  11. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i dont understand the whole vector and scalar thing

  12. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes, the i's "go away" you are left with 2j

  13. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    which is positive points?

  14. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    in 2-dimensions, you can think of the vector as <x,y> pair of numbers for example, u= -4i + 1j (which can also be written <-4,1> in a graph, it looks like this: |dw:1443634973472:dw|

  15. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    and the length of the vector is the length of the line from (0,0) (the origin) to the point (-4,1) we use pythagoras to find its length

  16. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    okay so U is a vector and length would be to the point.

  17. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oh okay i didnt see your message

  18. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    u+v = 2j (or 0i+2j, or (0,2) ) in a graph it looks like this |dw:1443635111360:dw|

  19. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1443635167339:dw|

  20. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    we could use pythagoras \[ \sqrt{0^2+2^2}= \sqrt{0+4}= \sqrt{4}= 2 \] but we can see the length is just 2

  21. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oh cool good so our drawings of vthis match okay so 0^2 because we have no i left and 2^2 becayse 2j

  22. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i understand thank you so much... can i ask what do i and j standfor why not use x and y? i got behind and i am trying to catch up on things as its obvious i am missing a gfew things in my knowledge

  23. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    The interesting thing is this same idea works for 3-D or even higher dimensions (though visualizing a vector with more than 3 components is beyond me)

  24. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I'm not sure why people use i,j,k but it does not matter the idea is they are different "dimensions" for example, sideways and up/down. The other way people write vectors is as a "tuple" such as (1,2) or <1,2> where it is understood each number is the distance along each dimension

  25. nthenic_oftime
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    okay so vectors would be written as plot points or coordinates just signified as different dimensions thanks for the help on the problem and that little info there it caught me up a lil bit. medal and fan for you :)

  26. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.