A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

@robtobey A geometric sequence is obtained by placing five terms between 10 and 640. What is the common ratio equal to ?

  • This Question is Open
  1. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    If r is the common ratio, then what is the next term right after 10?

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

    nothing the question was just like this

  3. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    do you agree that it would be 10*r or 10r ?

  4. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    since to get the next term, you multiply the last term by r hopefully that makes sense

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

    nope mate the answer will be 4 2 3 5 or 6

  6. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    don't worry about the answer choices right now

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

    ok

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

    11

  9. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    idk what you mean the term that comes after 10 is 10r the term after 10r is 10r*r = 10r^2 etc etc until you get to 640

  10. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    you should get this sequence: 10, 10r, 10r^2, 10r^3, 10r^4, 10r^5, 640

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

    ok

  12. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the next term after 10r^5 is 10r^6 therefore, 10r^6 = 640

  13. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    solve 10r^6 = 640 for r to get your answer

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

    which is 4

  15. zzr0ck3r
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I agree, to see an example look at 1,2,4,8,16,32,64 64/1=2^6

  16. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    r = 4 is false

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

    sorry it will be 2

  18. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    r = 2 is true

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

    thanks man can I ask 1 more question

  20. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    sure

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

    thank you then now I am writing

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

    |dw:1439165401472:dw|

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

    Did you get the question because my drawing is not good enough ?

  24. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    what is the area of the circle given

  25. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    hint: use A = pi*r^2

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

    it has given no area

  27. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    use that formula I gave to compute the area

  28. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    r = 5 in this case

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

    ok but how

  30. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    A = pi*r^2 A = pi*5^2 A = ???

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

    25pi then wat will happen

  32. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    now we will have another circle with the same center at point A this new circle will have radius 3 |dw:1439165882115:dw|

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

    ok

  34. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the goal is to find the area of this shaded region and divide it by the 25pi found earlier |dw:1439165892979:dw|

  35. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    what is the area of the smaller circle?

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

    9pi

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

    but the answer is not 9/25 mate

  38. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    it would be 9pi/25pi = 9/25 IF we wanted to land inside the inner circle but we want to land in that ring I shaded above

  39. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    area of ring = (area of larger circle) - (area of smaller circle)

  40. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    answer = (area of ring)/(area of larger circle)

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

    yes which will be 16/25

  42. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    good

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

    can I ask more please

  44. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    one last one

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

    ok

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

    1 Attachment
  47. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    which one?

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

    10

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

    if you can all of them :D

  50. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    are you able to compute f ' (x) ?

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

    not at all

  52. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    |dw:1439166519002:dw|

  53. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    what is the derivative of sin(x) ?

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

    cosx

  55. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    so we just derive the outer function sin(...) to get cos(...) |dw:1439166578842:dw|

  56. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    then we use the chain rule to derive cos(x) to get -sin(x) so derive cos(...) to get -sin(...) that gets multiplied to what we have |dw:1439166647000:dw|

  57. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    we then go in further derive 5x to get 5 that gets tacked on too |dw:1439166679192:dw| I placed it up front

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

    ok

  59. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    so \[\Large f \ ' (x) = 5\cos(\cos(5x))*(-\sin(5x))\]

  60. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    now just replace every x with pi/10 and evaluate

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

    ok

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

    the answer I think will be -5

  63. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yep it's -5

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

    can I PLease PLease ask one more question

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

    just one more and thats it

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

    thank you

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

    1 Attachment
  68. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    57

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

    did you find the answer mate

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

    Recall that \(sec^2(x) - tan^2(x) =1 \) \(cos^2(x) - cos(x)sin(x) = cos^2(x)[1 - tanx] = \frac{1}{sec^2(x)}[1-tanx] = \frac{1}{1+tan^2(x)}[1-tan(x)]\) Now put the value of tan(x) that's given.

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

    ok carry on

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

    * \(\frac{1}{1+tan^2(x)}[1-tan(x)]\)

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

    yeah but thats not my answer

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

    Substitute the tan(x)= 2 and get the answer.

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

    wat you think will be the answer

  76. 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.