# Finding the eq. of tangent line to this curve..

• June 17th 2012, 07:47 PM
kwonypoo
Finding the eq. of tangent line to this curve..
Hi! I'm struggling with this problem
Find an equation of the tangent line to the curve
http://webquiz.ilrn.com/ilrn/formula...%7D%7D%7D&tr=1 at the point (1, 8).
I am stuck because while I'm solving this, I keep getting 0/0.
How would you solve this problem?
Thanks!
• June 17th 2012, 08:04 PM
Cbarker1
Re: Finding the eq. of tangent line to this curve..
1. Find the differentiated function.
2. put in the (x,y) in the f'(x).
3. write the slope-pt form.
• June 17th 2012, 08:06 PM
richard1234
Re: Finding the eq. of tangent line to this curve..
Rewrite as $y = 8x^{-\frac{1}{2}}$.

$\frac{dy}{dx} = -4x^{-\frac{3}{2}}$. At the point (1,8), $\frac{dy}{dx} = -4$.

Write the equation of the tangent line in point-slope form: $y - 8 = -4(x-1)$.