Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Sgstudent

  • 2 years ago

Given that 5x^3 + 6x^2 -x + 2 = (x+1) (x-2) Q(x) + ax + b find the value of a and b. Question on Identities :)

  • This Question is Closed
  1. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Q(x) is an unknown polynomial?

  2. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea

  3. nphuongsun93
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    then... a = -1, b = 2?...dont think it should be this simple

  4. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that isnt the answer lol

  5. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    answer is a = 20 b = 24

  6. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    but i cant get it :(

  7. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    if Q(x) = 5x-9 ?

  8. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    o..o maybe you could work out the full solution and see if it matches my answer :P

  9. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you.

  10. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    \[ (x+​1)*​(x+​2)*​(5*​x-​9) = 5x^3 + 6x^2 -17x - 18 + 16x +20=5x^3 + 6x^2 -x + 2\]

  11. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    @Sgstudent

  12. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oo then how should i carry on

  13. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    hmm a is 16 and b is 20 for me

  14. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    check for any careless mistake? :O

  15. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    no i don't think so

  16. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    can you upload the picture of your working?

  17. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    i didn't do it on my notebook, in head.

  18. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    \[(x+​1)(x+​2)(5x−​9) +ax + b = 5x^3+6x^2−17x−18+ ax+b\]

  19. cwrw238
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    i did it also and got same result as ishaan

  20. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i need the working :(

  21. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or rather simple explanation towards the steps

  22. cwrw238
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    equating coefficients of x gives -1 = 10 - 27 + a a = 27-11 = 16

  23. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    use q(x) as px +q, suggested by you earlier if you really need to show working

  24. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    can i let Q(x) = px + q will i be able to get the answer?

  25. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh but i cant seem to get the answer somehow :(

  26. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i get decimal numbers :(

  27. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    show me your working i will try to guide you

  28. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    kk i try again

  29. Ishaan94
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well you can get multiple answers, maybe.

  30. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    only a and b

  31. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    (x+1) (x-2) *********

  32. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ishaan i edited the question

  33. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sry about it

  34. cwrw238
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    i can see how ishaan got p = 5 because of the 5x^3 but the q = -9 is not obvious = 5x^3 + 15x^2 + 10x + qx^2 + 3qx + 2q + ax + b = 5x^3 + (15 + q)x^2 + (10 + 3q + a)x + 2q + b compare coefficients with 5x^3 + 6x^2 - x + 2 of x^2: q + 15 = 6 so q = -9 of x: 10 + a + 3q = 10 + a - 27 = a - 17 and a -17 = -1 so a = 16 of x^0 : 2q + b = 2 so -18 + b = 2 so b = 20 a=16, b = 20

  35. Sgstudent
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks :)

  36. cwrw238
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yw

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

    Search OpenStudy
    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

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.