Thread: extremum

Find all extrema in the interval if y=x + sin x.

First, find your derivative.





What solutions to this fall in your interval?.

Here's a graph. They always help.

is it

a)
b) (0,0)
c)
d) (0,0)
e) None of these

Originally Posted by Samantha

is it

a)
b) (0,0)
c)
d) (0,0)
e) None of these

Have you looked at Galactus's plot? Are there any local maxima or minima?
Where are the global maximum and minimum in ?

RonL

Originally Posted by CaptainBlack

Have you looked at Galactus's plot? Are there any local maxima or minima?
Where are the global maximum and minimum in ?

RonL

I'mnot sure =(

I'm sorry to say, you should see your professor if you're that lost.

That's how I did it and understand it. Plz help

y=x+sinx
y(prime)=1+cosx
cosx=-1
x=

so the answer it

Originally Posted by Samantha

That's how I did it and understand it. Plz help

y=x+sinx
y(prime)=1+cosx
cosx=-1
x=

so the answer it

Evidently from the graph the function only has extrema at the ends of the interval since it is monotonically increasing. So the extrema are at x = 0 and x = 2*pi.

-Dan

Originally Posted by topsquark

Evidently from the graph the function only has extrema at the ends of the interval since it is monotonically increasing. So the extrema are at x = 0 and x = 2*pi.

-Dan

Then the answer is (0,0)?

Originally Posted by Samantha

Then the answer is (0,0)?

Looks like it. The critical points within the interval are obviously not relative max or min points (which you can tell by graphing or the second derivative test, whichever you prefer.)

-Dan