Thread: Tangen Line Equation Problem???

1. Tangen Line Equation Problem???

Find an equation for the line tangent to the graph of
at the point (2, 0.857142857142857).
=

2. see this thread ...

http://www.mathhelpforum.com/math-he...gent-line.html

btw, why the decimal for $\displaystyle \frac{6}{7}$ ?

you uncomfortable with fractions?

3. this is what they gave me in the problem

4. I tried to use that link but i am still coming up with the wrong answer.

could someone possible walk me through it?

5. what did you get for the derivative of $\displaystyle f(x)$?

6. 15/(x+5)^2

7. good.

the slope of the tangent line is $\displaystyle f'(2) = \frac{15}{(2+5)^2} = \frac{15}{49}$

use the point-slope form for a linear equation ...

$\displaystyle y - \frac{6}{7} = \frac{15}{49}(x - 2)$

this is the tangent line equation in point-slope form.

if you need to change it to standard form, multiply both sides by 49 to clear the fractions and manipulate accordingly.

8. Thanks again skeeter. I was so close!!!