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hba

  • 2 years ago

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

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  1. hba
    • 2 years ago
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    I got 10.

  2. waterineyes
    • 2 years ago
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    Really??

  3. hba
    • 2 years ago
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    Yeah really.

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

  5. hba
    • 2 years ago
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    Thanks.

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

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

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

  9. waterineyes
    • 2 years ago
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    First, we will take derivative.. Right??

  10. hba
    • 2 years ago
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    Yeah.

  11. waterineyes
    • 2 years ago
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    So wait, I am doing it..

  12. hba
    • 2 years ago
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    okay :(

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

  14. sirm3d
    • 2 years ago
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    there are two extrema, 1 relative maximum and 1 relative minimum.

  15. waterineyes
    • 2 years ago
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    Should I factorize it??

  16. hba
    • 2 years ago
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    put f'(x)=0

  17. waterineyes
    • 2 years ago
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    Yes I mean the same..

  18. hba
    • 2 years ago
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    Then the answer is yes

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

  20. waterineyes
    • 2 years ago
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    x = 5 and x = 1

  21. hba
    • 2 years ago
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    Yes you are right

  22. hba
    • 2 years ago
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    Now put 1 in the orignal equation.

  23. waterineyes
    • 2 years ago
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    Why not 5 ??

  24. hba
    • 2 years ago
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    Because we are finding the relative maxima

  25. waterineyes
    • 2 years ago
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    f(1) = 10

  26. sirm3d
    • 2 years ago
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    oooh, i misread the problem. relative maxima.

  27. hba
    • 2 years ago
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    Correct.

  28. waterineyes
    • 2 years ago
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    So, we have to put smaller value??

  29. hba
    • 2 years ago
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    Yes.

  30. waterineyes
    • 2 years ago
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    Just checking your answer.. Ha ha ha..

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

  32. hba
    • 2 years ago
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    |dw:1355817149046:dw|

  33. hba
    • 2 years ago
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    @waterineyes Check these two questions.

  34. waterineyes
    • 2 years ago
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    How to solve these now??

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

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

  37. hba
    • 2 years ago
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    So i am right ?

  38. waterineyes
    • 2 years ago
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    Are you sure it is e ??

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

  40. waterineyes
    • 2 years ago
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    You have used division rule here??

  41. hba
    • 2 years ago
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    U/V form.

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

  43. hba
    • 2 years ago
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    Wait lemme check.

  44. waterineyes
    • 2 years ago
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    Take your time..

  45. hba
    • 2 years ago
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    Yeah right

  46. hba
    • 2 years ago
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    @waterineyes ?

  47. waterineyes
    • 2 years ago
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    Who is right??

  48. hba
    • 2 years ago
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    The most intelligent @waterineyes

  49. waterineyes
    • 2 years ago
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    Not intelligent as you @hba

  50. waterineyes
    • 2 years ago
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    Now, find the second derivative..

  51. hba
    • 2 years ago
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    Ha Ha Ha Yeah wait.

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

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

  54. waterineyes
    • 2 years ago
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    Sorry busy helping other person..

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

  56. waterineyes
    • 2 years ago
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    Wait, let me check..

  57. hba
    • 2 years ago
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    ok

  58. waterineyes
    • 2 years ago
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    You can add first two terms in the numerator..

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

  60. hba
    • 2 years ago
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    @waterineyes So ?

  61. hba
    • 2 years ago
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    @waterineyes Ansoo kahan ho tum ?

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

  63. waterineyes
    • 2 years ago
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    Now what to do next??

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

  65. waterineyes
    • 2 years ago
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    There??

  66. hba
    • 2 years ago
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    yeah

  67. hba
    • 2 years ago
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    @waterineyes Where should i continue ?

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

  69. hba
    • 2 years ago
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    put it equal to 0

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

  71. waterineyes
    • 2 years ago
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    Where are we going?? Is that right??

  72. hba
    • 2 years ago
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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 ?

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

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

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

  76. hba
    • 2 years ago
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    Gurpreet :/ Chalo Bye.

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