# Thread: Equation of the Tangent...

1. ## Equation of the Tangent...

If f(x) = 1/x, find f'(3) and use it to find the equation of the tangent to the curve y = 1/x at the point (3, 1/3).

I found the slope to be -1/9 but I don't know how to find the equation

2. You have done
$
f(x)= \frac{1}{x}
$

$
\frac{dy}{dx}= \frac{-1}{x^2}
$

And thus got answer $\frac{-1}{9}$

Now equation of a line ,passing through (a,b),with a slope "m" is given by

$
(y-b)=m(x-a)
$

So the answer is

$
(y-\frac{1}{3}) = \frac{-1}{9} (x-3)
$

3. Oh I got it...The answer was just written differently than I had my answer ahah...thanks though