Are endpoints also critical points?

Question

I'm trying to find the critical points of a function on the interval [-1,5]. So far,the only critical point I have is 2. Does that mean -1 and 5 are also critical points?

Answer 1

only if it is horizontal there.
http://www.google.com/search?q=critical+point+of+function&ie=utf-8&oe=utf-8

Answer 2

I hope it was not you who posted this earlier, where I explained it all.

http://www.jiskha.com/display.cgi?id=1489049850

Answer 3

Yeah, how dare I ask for clarification on something I'm trying to understand.