Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

mathcalculus

  • one year ago

Help (Attached below) Determine the extrema of below on the given interval

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

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

    i know we have to find the derivative and set it to zero

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

    i got x= 8 and x= 2/9

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

    now to have the intervals, im a little lost on...

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

    would there only be 2 intervals?

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

    or 3? 0-2/9 then 2/9-8 and 8-infinity?

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

    ok... so whats the derivative...?

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

    9x^2-74x+16

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

    then i set it to = 0

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

    ok... so what are the solutions...?

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

    x=8 and x=2/9

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

    critical numbers

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

    yep... so on [0, 4] substitute x = 0, 2/9 and 4 into the original equation and find the corresponding values...

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

    why 4?

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

    thanks

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

    isn't 4 a y?

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

    and what 8?

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

    because the 2 critical numbers are 8 and 2/9

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

    well (a) is asking for the location of that min and max on the interval x = 0 to x = 4 and as x = 2/9 is a critical point...you don't know its nature

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

    ooooooh, 8 would be the other one

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

    let me try it

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

    so the value x =0 is f(0) = 2 x = 2/9 f(2/9) = 3.76 x = 4 f(4) = ?

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

    -334

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

    so the max is 3.76 and min is -334?

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

    thats correct...

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

    so just test x = -9, x = 8 and x = 9... and see what happens... I think x = 2/9 remains the max

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

    its an add interval since x = -9 gives a very large negative number

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

    • 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.