Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

ambeeeerlw Group Title

I don't understand the x and y determinant. will someone explain it with an example? I'm needing solve some like this: x + y = 12 x - y = 10 What is the value of the x-determinant for the system shown?

  • 3 months ago
  • 3 months ago

  • This Question is Open
  1. HourglassMage Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    add both equations

    • 3 months ago
  2. HourglassMage Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    you'll get 2x = 22

    • 3 months ago
  3. HourglassMage Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    solve for that, and you'll get 11

    • 3 months ago
  4. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I though that too, but that's not an answer. :(

    • 3 months ago
  5. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    thought*

    • 3 months ago
  6. HourglassMage Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    what are the options?

    • 3 months ago
  7. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    -22 -12 -2

    • 3 months ago
  8. HourglassMage Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I have to go, I'll respond to this in a little bit. Sorry.

    • 3 months ago
  9. tkhunny Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    x + y = 12 x - y = 10 D = (1)(-1)-(1)(1) Dx = (12)(-1)-(10)(1) Dy = (1)(10)-(1)(12)

    • 3 months ago
  10. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    That's fine. Thanks though :)

    • 3 months ago
  11. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Are you saying it's -22? It's asking for the x determinant if you're wondering. I just want to be able to solve the future ones. :)

    • 3 months ago
  12. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    @ambeeeerlw : Determinants are not used much any longer. However, you're apparently expected to know how to apply determinants to solving systems of linear equations. Have you tried looking up "determinants" on the 'Net? If you want to learn how do use determinants, either @tkhunny or I would be happy to help you ... but we do not give out just answers.

    • 3 months ago
  13. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I actually wasn't expecting just answers, I was double checking his work so I'd know how to future problems. I'm not trying to just collect answers, I swear. I have looked it up, but I can;t a way that explains it well enough where I fully understand. :( Can you help me?

    • 3 months ago
  14. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    ( or her work, I didn't see who it was)

    • 3 months ago
  15. tkhunny Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    "Cramer's Rule" is very interesting. It just works. It leans toward what we like to call an "Existence" result. This means it may or may not be very useful in the real world, but it demonstrates that (or under what conditions) the solution exists. Good thing to know.

    • 3 months ago
  16. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    My teacher didn't even mention it is "Cramer's Rule," so that's a nice factor to know.. I do online school, and I can't really get it touch with my teacher, reasoning behind me getting help from her.

    • 3 months ago
  17. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    @tkhunny typed this out for you earlier: x + y = 12 x - y = 10 D = (1)(-1)-(1)(1) Dx = (12)(-1)-(10)(1) Dy = (1)(10)-(1)(12) First, he found the "system determinant." He realized that x + y = 12 x - y = 10 can be re-written as 1x+1y=12 1x-1y=10 which we need to do because we need those coefficients of x and y. Notice how the coefficients (alone) are 1 1 1 -1 tkhunny now finds the "system determinant."|dw:1396529907980:dw|

    • 3 months ago
  18. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    The result is -1 -1, or -2. The system determinant is -2. Note that this is exactly the result obtained by tkhunny earlier. Have you seen this kind of work done before?

    • 3 months ago
  19. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes, that is the only one have and that I understand.

    • 3 months ago
  20. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Good. Now we need to find x. We take the system determinant, toss out the first column, and replace it with the constants (12 and 10):|dw:1396530274277:dw|

    • 3 months ago
  21. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    the products of those would be -12 and -10, right?

    • 3 months ago
  22. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Right, and that adds up to -22. Thus, your x is found in this manner:|dw:1396530623039:dw|

    • 3 months ago
  23. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    10?

    • 3 months ago
  24. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    close. Try again.

    • 3 months ago
  25. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    and your y value is

    • 3 months ago
  26. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I meant 11, oops :p

    • 3 months ago
  27. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    y value is 1? I think

    • 3 months ago
  28. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    |dw:1396530712310:dw|

    • 3 months ago
  29. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Cool. Yes, y=1. Solution is (11,1). congrats!

    • 3 months ago
  30. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I don't understand because the answers are only -22,-12, and -2. This is what confuses me

    • 3 months ago
  31. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Is it asking for another part of the question? I'm unsure.

    • 3 months ago
  32. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    @tkhunny's "answers" are intermediate results. He gave you D=-2, Dx = -22 and Dy = -2.|dw:1396531164233:dw|

    • 3 months ago
  33. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh, I apologize. So, basically the Dy and Dx are supported off of the system determinate?

    • 3 months ago
  34. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    that's right!! they are both modifications of the system determinant.

    • 3 months ago
  35. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    And nothing to apologize for! I so much appreciate your sticking with this until completion. Hope to get to work with you again.

    • 3 months ago
  36. ambeeeerlw Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Okay!!! That helps tremendously!! Thank you sososo much!!! I now understand :D

    • 3 months ago
  37. mathmale Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    That's like music to the ears! :)

    • 3 months ago
    • Attachments:

See more questions >>>

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.