Below is a graph on which four points have been labeled. At which of the points does the tangent line not exist?

<a> Point A

<b> Point B

<c> Point C

<d> Point D

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- May 24th 2006, 11:55 AMbobby77please help-urgent
Below is a graph on which four points have been labeled. At which of the points does the tangent line not exist?

<a> Point A

<b> Point B

<c> Point C

<d> Point D - May 24th 2006, 12:13 PMtopsquarkQuote:

Originally Posted by**bobby77**

Specifically look at point B. As we approach it from the left side, the tangent line has a negative slope. As we approach it from the right side, the tangent line has a positive slope. Since these two slopes don't agree, there is no tangent line at point B.

Check for yourself to make sure you can apply this argument to see why points A, C, and D have tangents at those points.

-Dan