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Math Help - Help with finding an equation of the tangent of f(x)

  1. #1
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    Help with finding an equation of the tangent of f(x)

    The question reads

    Determine the equation of the tangent to y = ln x at x = e

    Now I know how to find the equation using a regular function, but where Im confused is how to go about the x = e. Do I read that as e^1 which = 1 and then go from there, or does my final equation have e in it?

    Thank You!
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  2. #2
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    Quote Originally Posted by Meeklo Braca View Post
    The question reads

    Determine the equation of the tangent to y = ln x at x = e

    Now I know how to find the equation using a regular function, but where Im confused is how to go about the x = e. Do I read that as e^1 which = 1 and then go from there, or does my final equation have e in it?

    Thank You!
    dy/dy = 1/x. Therefore m = 1/e. And the point (e, 1) lies on the tangent. Now get the equation of the line in the usual way.
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  3. #3
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    Im kind of confused on what to do with this.

    I have y - 1 = 1/e(x-e) somehow I get y = x + 1
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  4. #4
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    Quote Originally Posted by Meeklo Braca View Post
    Im kind of confused on what to do with this.

    I have y - 1 = 1/e(x-e) somehow I get y = x + 1
    y - 1 = \frac{1}{e} (x - e) \Rightarrow y - 1 = \frac{x}{e} - 1. I just don't see how you can get y = x + 1 from this ....
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  5. #5
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    Ill try that thank you!
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