A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • 5 years ago

plzz help ... Solve each polynomial equation 1. 15x^3-119x^2-10+16=0 2. x^3-14x^2+47x-18=0 3. 5x^3-27x^2-17x-6=0

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

    I notice that these are all cubics. So I would first try to factor by grouping and if that doesn't work, then try synthetic division.

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

    thank u

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

    how do i do synthetic division with no divisor or watever its called?

  4. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Let's look at the first one.. The constant term is 16 and the coefficient of the x^3 term is 15. So the possible rational roots are the factors of 16 over the factors of 15 Use those for your "shelf" numbers in the synthetic division process. If you get a remainder of 0, that number is a root.

  5. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    So the possible rational roots are:\[\pm1, \pm2,\pm4,\pm8,\pm16,\pm1/3,\pm1/5,\pm1/15,\pm2/3,\pm4/3,\pm8/3,\pm16/3,\pm2/5,\pm4/5\]

  6. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    and so on

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

    so i take the numbers and do what?

  8. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1327020100318:dw|

  9. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    So we see that 8 is a root and (x-8)(15x^2+x-2) are factors.

  10. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Take the second factor 15x^2+x-2 and use the quadratic formula on it and find the other roots.

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

    so then the answer is 15x^2-x-2x omg thaks i get it!!!

  12. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I actually cheated and used a graphing calculator to find the 8

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

    not 2x sorry

  14. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    No that is not the answer. The 3 answers are 8 and whatever you get when you solve 15x^2+x-2=0

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

    ohhh so how do i find that out?

  16. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Don't you know how to solve a quadratic equation with the quadratic formula?

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

    is that the -b +or - one?

  18. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes

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

    sweet i get it now thank you!!!

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

    \[\left\{5 x^3-119 x^2-10 x+16=0,(x-8) (3 x-1) (5 x+2)=0\right\}\left\{x^3-14 x^2+47 x-18=0,(x-9) \left(x^2-5 x+2\right)=0\right\}\left\{5 x^3-27 x^2-17 x-6=0,(x-6) \left(5 x^2+3 x+1\right)=0\right\} \]

  21. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1327020932580:dw|

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

    i got for the first one -1|dw:1327021163596:dw|

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

    |dw:1327021250750:dw| this is the answer??

  24. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Don't you see where I solved it for you?

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

    oh sorry i wasnt looking .. lol

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

    i see it now

  27. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok

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

    thanks sooo much

  29. Mertsj
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yw

  30. 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.