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

znimon

How do I find the domain of this function?

  • one year ago
  • one year ago

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

    \[g(x) \sqrt{x^2 - 3x - 40}\]

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

    I have \[\sqrt{(x-8)(x+5)} \]

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

    \[(x-8)(x+5) \ge 0\]

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

    The original problem is at the top.

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

    Draw a number line and see for it

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

    I don't know what x can't be though

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

    I know the answer but I don't know how to get the answer.

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

    (-infinity , 5] U [8 , infinity)

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

    yeah but how do I find that?

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

    just do trial and error method...)

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

    (x−8)(x+5)≥0

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

    luk for the vlue of x which satisfies this...

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

    There must be a logical way to find the answer, right?

    • one year ago
  14. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    (x-8)(x+5) >= 0 its a parabola, right ?

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

    I could input it into my graphing calculator but other wise I don't know how to tell if its a parabola or not.

    • one year ago
  16. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    y = ax^2 + bx + c is a parabola

    • one year ago
  17. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    any quadratic function gives a parabola graph

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

    ok

    • one year ago
  19. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    can you find the x intercepts ?

    • one year ago
  20. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    once you find x-intercepts, you would know where the parabola dips into x axis (goes negative)

    • one year ago
  21. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    |dw:1346519548989:dw|

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

    Oh ya that would be the point at which the g(x) function is 0, so its x - 8 = 0, x = 8, x+ 5 = 0, x=-5, and since its a parabola the graph only passes through zero twice. Nice dude, so the domain is (-infinity, -5] U [8, +infinity]

    • one year ago
  23. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    yeah nice you got it :)

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

    @ganeshie8

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

    Awesome, thanks again. Is there a way I could recognize any graph's shape or at least some and would you recommend memorizing those?

    • one year ago
  26. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    if the degree is 2, then its a parabola

    • one year ago
  27. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    finding domains for other polynomials is bit tricky... as they may dip into x-axis multiple times

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

    okay

    • one year ago
  29. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    do you knw sketching polynomilas (end behiavior thingy )

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

    never heard of it

    • one year ago
  31. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    end behavior helps you sketch ANY polynomial freehand

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

    Thanks dude, I'll look it up

    • one year ago
  33. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    process is basically : 1) find x intercepts 2) using end-behavior sketch the graph by hand

    • one year ago
  34. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    its easy concept and worth learning... im sure you wil get hang of it in few minutes....... good luck :)

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

    why is it that a polynomial with a degree of two is a parabola?

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

    Thanks again.

    • one year ago
  37. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    uhh il have to think...... idk exactly... i think it has something to do with local maximum/minimum + increasing/decreasing thingy. we need to turn to calculus for proper understanding. im also learning... . so im no good for answering this :(

    • one year ago
  38. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    @mukushla @eliassaab @experimentX

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

    Oh, I have enough to learn for now so it doesn't matter to me. I bet I wouldn't understand the explanation if it involves terms I've never had before haha.

    • one year 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.