• Support PF! Buy your school textbooks, materials and every day products Here!

Local maximum point

  • Thread starter Joza
  • Start date
139
0
Local maximum point......

1. Homework Statement

f(x)=xe TO THE POWER OF -ax


x E R


a > o

Show that f(x) has a local maximum and express this point's coordinates in terms of a.


3. The Attempt at a Solution

I think dy/dx = -axe TO THE POWER OF -ax

Correct?

I don't know where to go after this.
 

Answers and Replies

Dick
Science Advisor
Homework Helper
26,258
618
Your derivative is wrong. Remember the product rule?
 
139
0
Oh product.........

Ok so....... xe^-ax + e^-ax(1)

Is that right?
 
Dick
Science Advisor
Homework Helper
26,258
618
You used to have a (-a) in front of the first term. Where did that go? I liked it.
 
139
0
Ok, I mie be wrong here.

(u)dv/dx + (v)du/dx

So..... (x)-ae^-ax + e^-ax( 1) = -axe^-ax + e^-ax

Correct?
 
Dick
Science Advisor
Homework Helper
26,258
618
Finally! Rest of the problem is easy, right?
 
139
0
I let it = 0 and solve to get values for x?
 
Dick
Science Advisor
Homework Helper
26,258
618
I think so. Correct me if I'm wrong. :smile:
 
HallsofIvy
Science Advisor
Homework Helper
41,732
893
Now, Dick, have you ever been wrong?
 
Dick
Science Advisor
Homework Helper
26,258
618
More times than I can count. I was betting on the Bears last night.
 

Related Threads for: Local maximum point

  • Last Post
Replies
11
Views
644
  • Last Post
Replies
12
Views
1K
  • Last Post
Replies
21
Views
4K
  • Last Post
Replies
3
Views
534
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
2
Views
1K
Replies
1
Views
1K
  • Last Post
Replies
9
Views
4K
Top