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Math Help - Finding equation of a tangent line.

  1. #1
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    Finding equation of a tangent line.

    first i had to find the derivation of a function, and i found that to be
    g'(t)= 2/(t+3)^2

    now i'm asked to find the equation of the tangent line when t = -5
    so i figured id plug -5 into the above equation and i ended up with:

    2/(-5+3)^2= 1/2
    So that means i have two points an x and a y

    -5,1/2

    This is where im stuck how can i find a slope with this information so i can write on the tangent equation?
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  2. #2
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    You found the slope of the tangent line to be 1/2 = 0.5. Let y = g(t). Then the tangent line can be expressed as y - y_1 = 0.5(t - t_1). But t_1 = -5 so the line is y - y_1 = 0.5(t + 5). You have to calculate the value of the function y_1 = g(t_1) = g(-5).
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  3. #3
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    g(-5) as in using the original function i had before g(t)=2/t+3 not the derivative function?
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  4. #4
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    Quote Originally Posted by excelsion View Post
    g(-5) as in using the original function i had before g(t)=2/t+3 not the derivative function?
    Yes.
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