Quantcast

A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

mathcalculus

  • 2 years ago

mathcalculus HELP: Determine the values of where the tangent line is horizontal for the function:

  • This Question is Closed
  1. mathcalculus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

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

    i know i have to find the derivative and set it to zero but it's not coming out to be correct. can anyone help me

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

    so i did 3x^2-6x-4=0

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

    i tried to use the quadratic formula and got sqrt(21)+3/3

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

    + or - sqrt(21)+3/3

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

    also aka 2.52753...

  7. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    derivative seems correct

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

    to find what x = to... ?

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

    i used quadratic formula

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

    @dumbcow dont i have to do that to find x??

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

    im getting it wrong,

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

    yes everything looks correct to me...do they want exact or decimal answer?

  13. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    http://www.wolframalpha.com/input/?i=3x%5E2-6x-4%3D0

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

    can i use quadratic formula for ths one?

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

    @dumbcow

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

    ??

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

    ????????????????????????

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

    yes of course you use quadratic formula...thats how you got your answer that i said looked correct

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

    im not getting that using quadratic formula

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

    im getting something totally different and wrong

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

    \[x = \frac{3 \pm \sqrt{21}}{3}\]

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

    yes! but from 6+2*sqrt(21)/6?

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

    shouldnt it be 1+ or - sqrt 21/3

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

    same thing, just a matter of splitting up fraction or keeping it as single fraction

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

    no it's not because the answer is 1+ sqrt (7/3) gives me 2.52753 and 1+sqrt 21/3 gives me 1.86086!

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

    @dumbcow

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

    hmm \[\frac{\sqrt{7}}{\sqrt{3}} = \frac{\sqrt{21}}{3} \]

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

    hmmm?

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

    @dumbcow

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

    try it on a calculator.

  31. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    http://www.wolframalpha.com/input/?i=1%2Bsqrt%287%2F3%29+%2C+1%2Bsqrt%2821%29%2F3

  32. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oh you added the "1" before dividing by "3"

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

    okay from my answer.... not the internet.. 6+2 sort(21)/3.... where do i go from there?

  34. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    well it should be a 6 on bottom

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

    no i didn't add anything.

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

    okay sure a 6. i thought it could be a 3 to narrow it down

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

    so 6+or-2sqrt(21)/6

  38. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i dont see the problem, you posted answer in beginning... " i tried to use the quadratic formula and got sqrt(21)+3/3 "

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

    so it is a 3 in the denominator!

  40. dumbcow
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\frac{6 \pm 2\sqrt{21}}{6} = \frac{2(3 \pm \sqrt{21})}{6} = \frac{3 \pm \sqrt{21}}{3}\]

  41. 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.