# Tangen Line Equation Problem???

• October 3rd 2008, 01:30 PM
johnny4lsu
Tangen Line Equation Problem???
Find an equation for the line tangent to the graph of
• October 3rd 2008, 01:36 PM
skeeter

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

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

you uncomfortable with fractions?
• October 3rd 2008, 01:38 PM
johnny4lsu
this is what they gave me in the problem
• October 3rd 2008, 01:43 PM
johnny4lsu
I tried to use that link but i am still coming up with the wrong answer. (Headbang)

could someone possible walk me through it?
• October 3rd 2008, 01:51 PM
skeeter
what did you get for the derivative of $f(x)$?
• October 3rd 2008, 01:54 PM
johnny4lsu
15/(x+5)^2
• October 3rd 2008, 02:04 PM
skeeter
good.

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

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

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

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.
• October 3rd 2008, 02:10 PM
johnny4lsu
Thanks again skeeter. I was so close!!!