A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Mimi_x3

  • one year ago

help pls...i have no clue about this course

  • This Question is Closed
  1. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    https://gyazo.com/b7c760976b5d45ae89ade505c11949ff

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I can't open it, seems I need a proxy

  3. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    :|

  4. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    give me a sec

  5. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Sure you know that you need a substitution, right?

  7. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    what substitution

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sub \(y_1=f(x_1, x_2)\) and \(y_2=g(x_1, x_2)\) in a way that first two equations turn into second system in terms of \(y\)

  9. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I really don't know...can you please elaborate

  10. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I can't find anything related to this on google :/

  11. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    let \(y_1=x_1\) and \(y_2=x_1+x_2\) see what happens

  12. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    do i sub it into x dot?

  13. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sry, I was out, see for example\[\dot{y_1}=\dot{x_1}=x_1+x_2=y_2\]Now you calculate \(\dot{y_2}\)

  14. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Hey dont overthink it, this is just some algebraic manipulation, Its not weird

  15. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I don't get it why does y dot = x dot?

  16. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Its a dynamical system, dot is "derivative with respect to time" here

  17. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    dx/dt ?

  18. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    exactly

  19. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Now, what about \(\dot{y_2}\) ?

  20. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I don't get how the x is related to the y?

  21. UsukiDoll
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the dot isn't used that much , but it's another way of saying first derivative for a single dot 2nd derivative for a double dot.

  22. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    That depends on how we define y in terms of x, we do this sub to get a simpler form of equations that are easy to interpret physically

  23. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Think of it like this, you have a system of differential equations in x_1 and x_2 and you wanna solve it, you do a sub to get a simpler form and to solve it more easily

  24. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    And x is not related to y, we relate it to y :)

  25. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i don't get it y dot = -(2x + x)

  26. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    y dot = -(2x_1+x_2)

  27. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yeah my bad

  28. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok, let me explain it step by step

  29. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you have these system of equations:\[\dot{x_1}=x_1+x_2 \]\[\dot{x_2}=-2x_1-x_2\]

  30. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Now I do a sub in the form \(y_1=x_1\) and \(y_2=x_1+x_2\), lets see what happens

  31. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[\dot{y_1}=\dot{x_1}=x_1+x_2=y_2\]\[\dot{y_2}=\dot{x_1}+\dot{x_2}=x_1+x_2-2x_1-x_2=-x_1=-y_1\]

  32. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    how would you know what sub to do

  33. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that's just like integrals, how do you solve integrals with u-sub?

  34. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    by looking

  35. Mimi_x3
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    thanks

  36. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    No problem, skill develops with practice and experience

  37. Jack1
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    nice

  38. 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.