increasing, decreasing, concave up, and concave down help!

[hollahjinax3]

Hi, for example this problem relating to dervivatives..


y= x^2 -x -1


would I need to graph it in order to find the increasing, decreasing...etc...? or is it possible to use the first derviative test or something?


cuz im confused about if this type of problem would need to be graphed or to be done on paper?

 

[ChaoticLlama]

umm... you don't need calculus to graph this at all.

But if you were to

dy/dx = 2x - 1

set dy/dx = 0

2x = 1

x = 1/2

And I can tell you that x = 1/2 is the minimum of this function without the 1st derivative test since in the original function, the coefficient to the x² term is positive.

P.S. you are not making much sense in your post, in future, please read carefully what you type so that you are getting your questions across concisely.

 

[stapel]

What are the actual instructions? Are you graphing this? Or are you finding intervals of increase and/or decrease?

Please reply with the full text of the exercise, including the complete instructions.

Thank you.

Eliz.