September 17th, 2012, 09:33 AM  #1 
Newbie Joined: Sep 2012 Posts: 6 Thanks: 0  Critical point
What is the value of the xcoordinate of the critical point of f to 2 decimal places? f(x) = ln(x) + x^150 Any ideas guys? Thanks 
September 17th, 2012, 09:45 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 18,554 Thanks: 1479 
The value is 1.03, but you would need to use calculus to find it, so you've posted the question in the wrong subforum.

September 17th, 2012, 09:56 AM  #3 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,155 Thanks: 464 Math Focus: Calculus/ODEs  Re: Critical point
We are given: To find the critical point, differentiate and equate to zero: To approximate this root, we could use Newton's method: Using an initial guess of , we find after many iterations: 
September 17th, 2012, 10:51 AM  #4 
Newbie Joined: Sep 2012 Posts: 6 Thanks: 0  Re: Critical point
Thanks skipjack and MarkFL, I've made a typing error... it's supposed to be 140 instead 150. Any ideas what the answer will be? 
September 17th, 2012, 10:58 AM  #5 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,155 Thanks: 464 Math Focus: Calculus/ODEs  Re: Critical point
Then you would have: 
September 17th, 2012, 11:05 AM  #6 
Newbie Joined: Sep 2012 Posts: 6 Thanks: 0  Re: Critical point
Wow you guys are brilliant, thanks!


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