A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Which of the following is a root of the polynomial shown below? f(x)=x^3-4x^2-11x+30 A. -3 B. 0 C. 1 D. 6

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

    \[f(x) = x^3-4x^2-11x+30\] so given that polynomial, we need to use the rational root test. So using the last term (that's 30) find all factors of 30 plug in x = one of the factors of 30 and see if your result is 0 If it's 0, then we have a root If it's not 0 we don't have root and if all roots don't work, then the rational root test fails

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

    is it C?

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

    oh... we have multiple choice... that's good. We can use either -3,1, or 6. Hint: 0 doesn't work. Is it C? let's try it let x = 1 \[f(1) = 1^3-4(1)^2-11(1)+30\] try computing f(1)

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

    I got 1-16-11+30 = 0 unless I did something wrong

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

    something isn't right for the 4(1)^2 part

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

    (1)^2 means write 1 twice (1)(1) so for that part 4(1)(1) what's 4 x 1 x 1 ?

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

    oh oops is it 1-4-11+30=16 so it's not c?

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

    not c. so cross that out

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

    so it's either -3 or 6

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

    Oh I got it. I think it's a? -27-36+33-30=-0

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

    oops 0*

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

    \[f(-3) = (-3)^3-4(-3)^2-11(-3)+30\] \[f(-3) = -27-4(9)+33+30\] \[f(-3) = -27-36+33+30\] \[f(-3) = -63+63\] \[f(-3) = 0\] so yes -3 is a root of the polynomial you can just write 0. a negative sign isn't required.

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

    okay thanks!! I get it now :)

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

    yay :D

  15. 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.