Posted by Cecille on Wednesday, March 23, 2011 at 7:39pm.
Let f(x) = x^3  x^2 + x  1. Find an equation for tangent line to f at x = 2.

Calculus Please Help  TutorCat, Wednesday, March 23, 2011 at 8:10pm
x=2 could be rewritten as (2,0)
Look at example 1:
http://www.cliffsnotes.com/study_guide/TangentandNormalLines.topicArticleId39909,articleId39887.html 
Calculus Please Help  Reiny, Wednesday, March 23, 2011 at 9:49pm
f(x) = x^3  x^2 + x  1
f'(x) = 3x^2  2x + 1
when x=2 , f'(1) = 12  4 + 1 = 9
also when x=2, f(2) = 8  4 + 2 1 = 5
so the tangent has a slope of 9 and passes through (2,5)
equation of tangent is y = 9x + b
at (2.5)
5 = 9(2) + b
b = 13
equation of tangent: y = 9x  13