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hba

Checking my answers if f(x)=x^3-9x^2+15x+3 What is the relative maxima ?

  • one year ago
  • one year ago

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  1. hba
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    I got 10.

    • one year ago
  2. waterineyes
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    Really??

    • one year ago
  3. hba
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    Yeah really.

    • one year ago
  4. waterineyes
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    It will be right as it is calculated by the Great @hba ha ha ha..

    • one year ago
  5. hba
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    Thanks.

    • one year ago
  6. hba
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    I have more question to get checked can i ask here or in a new post.

    • one year ago
  7. waterineyes
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    I don't know how to solve these types of questions.. Can you teach me how to solve it..??

    • one year ago
  8. hba
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    @waterineyes Ha Ha Ha Nice joke,first let me ask my questions.

    • one year ago
  9. waterineyes
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    First, we will take derivative.. Right??

    • one year ago
  10. hba
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    Yeah.

    • one year ago
  11. waterineyes
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    So wait, I am doing it..

    • one year ago
  12. hba
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    okay :(

    • one year ago
  13. waterineyes
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    f'(x) = 3x^2 - 18x + 15

    • one year ago
  14. sirm3d
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    there are two extrema, 1 relative maximum and 1 relative minimum.

    • one year ago
  15. waterineyes
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    Should I factorize it??

    • one year ago
  16. hba
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    put f'(x)=0

    • one year ago
  17. waterineyes
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    Yes I mean the same..

    • one year ago
  18. hba
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    Then the answer is yes

    • one year ago
  19. waterineyes
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    \[x^2 - 6x + 5 = 0 \implies (x - 5)(x - 1) = 0\]

    • one year ago
  20. waterineyes
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    x = 5 and x = 1

    • one year ago
  21. hba
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    Yes you are right

    • one year ago
  22. hba
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    Now put 1 in the orignal equation.

    • one year ago
  23. waterineyes
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    Why not 5 ??

    • one year ago
  24. hba
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    Because we are finding the relative maxima

    • one year ago
  25. waterineyes
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    f(1) = 10

    • one year ago
  26. sirm3d
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    oooh, i misread the problem. relative maxima.

    • one year ago
  27. hba
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    Correct.

    • one year ago
  28. waterineyes
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    So, we have to put smaller value??

    • one year ago
  29. hba
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    Yes.

    • one year ago
  30. waterineyes
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    Just checking your answer.. Ha ha ha..

    • one year ago
  31. waterineyes
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    Now don't say, to find relative minima, we will put 5..

    • one year ago
  32. hba
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    |dw:1355817149046:dw|

    • one year ago
  33. hba
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    @waterineyes Check these two questions.

    • one year ago
  34. waterineyes
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    How to solve these now??

    • one year ago
  35. hba
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    I got f'(x)=e in both the cases.

    • one year ago
  36. hba
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    And f''(x)=1/e for 1st and f''(x)=e in the 2nd one.

    • one year ago
  37. hba
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    So i am right ?

    • one year ago
  38. waterineyes
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    Are you sure it is e ??

    • one year ago
  39. hba
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    Pretty sure Because i did this one like 100 times when i was in High school

    • one year ago
  40. waterineyes
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    You have used division rule here??

    • one year ago
  41. hba
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    U/V form.

    • one year ago
  42. waterineyes
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    For first : \[f'(x) = \frac{1 - \ln(x)}{x^2}\]

    • one year ago
  43. hba
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    Wait lemme check.

    • one year ago
  44. waterineyes
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    Take your time..

    • one year ago
  45. hba
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    Yeah right

    • one year ago
  46. hba
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    @waterineyes ?

    • one year ago
  47. waterineyes
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    Who is right??

    • one year ago
  48. hba
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    The most intelligent @waterineyes

    • one year ago
  49. waterineyes
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    Not intelligent as you @hba

    • one year ago
  50. waterineyes
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    Now, find the second derivative..

    • one year ago
  51. hba
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    Ha Ha Ha Yeah wait.

    • one year ago
  52. hba
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    I am getting something,which looks extremly wrong :/

    • one year ago
  53. hba
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    @waterineyes Here you go \[f''(x)=-x-2x+2lnx/x^4\] I kow it's wrong :/

    • one year ago
  54. waterineyes
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    Sorry busy helping other person..

    • one year ago
  55. waterineyes
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    Now I think, if it was e then it will be simpler..

    • one year ago
  56. waterineyes
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    Wait, let me check..

    • one year ago
  57. hba
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    ok

    • one year ago
  58. waterineyes
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    You can add first two terms in the numerator..

    • one year ago
  59. hba
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    Yeah i can add them so, \[f''(x)=-3x+2lnx/x^2\]

    • one year ago
  60. hba
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    @waterineyes So ?

    • one year ago
  61. hba
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    @waterineyes Ansoo kahan ho tum ?

    • one year ago
  62. hba
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    @waterineyes Answer tau sahi hai mera,Is ki working mushkil hai :/

    • one year ago
  63. waterineyes
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    Now what to do next??

    • one year ago
  64. waterineyes
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    I had a guest in home so busy there.. Sorry, let us now work together..

    • one year ago
  65. waterineyes
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    There??

    • one year ago
  66. hba
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    yeah

    • one year ago
  67. hba
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    @waterineyes Where should i continue ?

    • one year ago
  68. waterineyes
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    What we will do next after finding second derivative?? To find extreme value..

    • one year ago
  69. hba
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    put it equal to 0

    • one year ago
  70. waterineyes
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    \[2 \ln(x) = 3x\]

    • one year ago
  71. waterineyes
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    Where are we going?? Is that right??

    • one year ago
  72. hba
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    i think we should skip these lol,I am pretty sure about my answers :) Do you know what is a stationary point ?

    • one year ago
  73. waterineyes
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    The point which is stationary is called Stationary Point, that's it..!!!

    • one year ago
  74. hba
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    So, if f(x)=ln(1+x^2) What will be the stationary point ?

    • one year ago
  75. waterineyes
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    I think I should go now.. Ha ha ha.. Seriously, don't know..

    • one year ago
  76. hba
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    Gurpreet :/ Chalo Bye.

    • one year ago
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