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Math Help - Using Derivatives, find the equation of the tangent line.

  1. #1
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    Using Derivatives, find the equation of the tangent line.

    Using Derivitives, find the equation of the tangent line at the given point.

    x/(x-1) at the point (2,2).

    So I don't know whether to immediately use the quotient rule to find f'(x), then plug in x = 2 for f'(x). Am I going about this wrong?
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  2. #2
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    You are correct.Proceed.
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  3. #3
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    Quote Originally Posted by sa-ri-ga-ma View Post
    You are correct.Proceed.
    f'(x)=-1/[(x-1)^2], so then f'(2)=-1?

    is that correct, then what next?
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  4. #4
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    What does the derivative tell you about the tangent line?
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  5. #5
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    slope of the line its tangent to?
    so y=mx+b right?

    then f'(2)=-1 & f(x)=2, alright so here is where I'm stuck.

    I haven't had math in a year.
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  6. #6
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    Yes, use y = mx + c (or + b... haven't seen that, but it could work!)

    You should be able to replace all but the c with values, and solve to find the value of c. What role does m play? ... so you have it here by another name. Likewise y. And you know the value of x, of course. So deduce c.
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