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Math Help - Compute the indicated derivative...just need guidance

  1. #1
    JDS
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    Compute the indicated derivative...just need guidance

    I worked out my solution and was hoping for some input from the experts as to whether I did this correctly or not.

    Thanks in advance!!

    Compute the indicated derivative.

    f'''(t) for f(t) = 4t2 - 12 + (4/t2)

    F(t) = (d/dt) (4t2 -12 + (4/t2)

    = 8t + 4t-2

    F(t) = (d/dt) (8t + 4t-2)

    = 8 8t-1

    F(t) = (d/dt) (8 8t-1)

    = 8
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  2. #2
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    Re: Compute the indicated derivative...just need guidance

    Quote Originally Posted by JDS View Post
    Compute the indicated derivative.
    f'''(t) for f(t) = 4t2 - 12 + (4/t2)
    It is completely wrong.
    Write as: 4t^2-12+4t^{-2}
    Then
    8t-8t^{-3}
    8+24t^{-4}
    -96t^{-5}
    Thanks from JDS
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  3. #3
    JDS
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    Re: Compute the indicated derivative...just need guidance

    Wow, I don't know how I was so wrong! I think I need to go back and reread this chapter!!!
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  4. #4
    JDS
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    Re: Compute the indicated derivative...just need guidance

    Okay, so lets see if I understand this now...., lets use the following:

    Find the derivative:

    f(x) = (x^3/2 - 4x) (x^4 - 3/x^2 +2)

    then I would rewrite as........

    = (x^3/2 -4x) (x^4 - 3x^-2 + 2)

    then, take the derivative.......

    f ' (x) = [((3/2 x^-3/2) - 4)(x^4 - 3x^-2 +2)] + [(x^3/2 - 4x) (4x^2 + 3x^-3)]

    Ive got a headache now, btw
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  5. #5
    JDS
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    Re: Compute the indicated derivative...just need guidance

    bump
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  6. #6
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    Re: Compute the indicated derivative...just need guidance

    Quote Originally Posted by JDS View Post
    Okay, so lets see if I understand this now...., lets use the following:

    Find the derivative:

    f(x) = (x^3/2 - 4x) (x^4 - 3/x^2 +2)

    then I would rewrite as........

    = (x^3/2 -4x) (x^4 - 3x^-2 + 2)

    then, take the derivative.......

    f ' (x) = [((3/2 x^-3/2) - 4)(x^4 - 3x^-2 +2)] + [(x^3/2 - 4x) (4x^2 + 3x^-3)]
    Not quite, though the errrors may be typos. The derivative of x^(3/2) is (3/2)x^(3/2- 1)= (3/2)x^(1/2), not (3/2)x^(-3/2),
    the derivative of x^4 is 4x^(4- 1)= 4x^3, not 4x^2, and the derivative of 3x^(-2) is 3(-2)x^(-2-1)= -6x^(-3), not 3x^(-3).

    Ive got a headache now, btw
    Don't worry, you'll get used to it!
    Thanks from JDS
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  7. #7
    JDS
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    Re: Compute the indicated derivative...just need guidance

    Thanks! I've been pulling my hair out over this, lol!
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