A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Use synthetic division to determine whether the number k is an upper or lower bound (as specified) for the real zeros of the function f. k = 4; f(x) = 2x^3 - 2x^2 - 3x - 5; Lower bound?

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes or no are the answer choices

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

    @Loser66

  3. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    So, you have to solve for the zeros of the function. What are they?

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

    I'm honestly not sure how to find them

  5. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    use demos graph to see where they cut x-axis

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

    (2.2,0)

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

    So would the answer be no since it's (2.2,0) and 4 would be a higher bound and not lower bound?

  8. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    we don't have 0. please check

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

    what do you mean? it cut the x-axis at 2.2

  10. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    but you can use it. now find f(0) =?

  11. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    replace 0 into f(x) , what do you get?

  12. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442536923437:dw|

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

    -5

  14. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok, so f(0) =-5 < 0 , right? now f (2) =?

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

    -3

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

    So what does that mean

  17. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    that mean from 0 to 2 you still not pass the x-axis, since f(x) <0 for both. Now test f(3)

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

    22

  19. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes, so from 2 to 3 , f(x) go from negative to positive, that is you have one zero on that interval, right?

  20. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Now, use synthetic,

  21. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    forget it, short cut

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

    okay haha

  23. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442537533408:dw|

  24. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    now, fill up

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

    Again, the lesson didnt really explain this stuff so I'm not sure how to use that

  26. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    you don't know synthetic?

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

    not completely, looking it up now trying to learn real quick

  28. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442537680182:dw|

  29. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442537714109:dw|

  30. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    now 4 *6 =?

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

    24

  32. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442537779766:dw| got it?

  33. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    the last one, you do, the same

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

    would it be 4*21 = 84 or 4*24 =96?

  35. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442537857152:dw|

  36. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    you take 4 * the bottom row, put the result on the middle row of the new column, then add them up to get the new number.

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

    oh okay i see

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

    that's easy then haha

  39. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1442538058710:dw|

  40. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok, now, 4 >0 , right?

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

    yes

  42. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    look at the bottom row, they are 2,6,21,79 right?

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

    yes

  44. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    and all them are positive, right?

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

    yes

  46. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Hence 4 is upper bound for the zeros

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

    woah i see, a lot goes into it

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

    so back to the original question the answer would be no

  49. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yup

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

    ok thanks for all of the help, what would happen if one of them was negative?

  51. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    you test, if k <0, the bottom line is +, -,+,- alternatively, then k is lower bound

  52. Loser66
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    learn from it http://www.howe-two.com/mathematicat/bound.html

  53. 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.