Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

mathcalculus

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

  • 8 months ago
  • 8 months ago

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

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

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

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

    i got x= 8 and x= 2/9

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

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

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

    would there only be 2 intervals?

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

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

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

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

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

    9x^2-74x+16

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

    then i set it to = 0

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

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

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

    x=8 and x=2/9

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

    critical numbers

    • 8 months ago
  13. campbell_st
    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...

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

    why 4?

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

    thanks

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

    isn't 4 a y?

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

    and what 8?

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

    because the 2 critical numbers are 8 and 2/9

    • 8 months ago
  19. campbell_st
    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

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

    ooooooh, 8 would be the other one

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

    let me try it

    • 8 months ago
  22. campbell_st
    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) = ?

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

    -334

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

    so the max is 3.76 and min is -334?

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

    thats correct...

    • 8 months ago
  26. campbell_st
    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

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

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

    • 8 months ago
    • Attachments:

See more questions >>>

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.