February 12th, 2016, 04:24 PM  #1 
Newbie Joined: Feb 2016 From: Oregon Posts: 19 Thanks: 0  Critical Value Help
Let f(x) = 8√x − 6x for x > 0. Find the open intervals on which f is increasing/(decreasing). Then determine the xcoordinates of all relative maxima/(minima).
Last edited by skipjack; February 13th, 2016 at 12:12 AM. 
February 12th, 2016, 05:00 PM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 3,101 Thanks: 1677 
$f(x) = 8\sqrt{x}  6x$ what did you get as the derivative? 
February 12th, 2016, 09:14 PM  #3 
Newbie Joined: Feb 2016 From: Oregon Posts: 19 Thanks: 0 
I got f$\,'\!$(x) = 4x  6 as the derivative.
Last edited by skipjack; February 13th, 2016 at 12:04 AM. 
February 12th, 2016, 09:23 PM  #4 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,700 Thanks: 2682 Math Focus: Mainly analysis and algebra 
Not ${4 \over \sqrt x}6$?

February 13th, 2016, 05:11 AM  #5 
Math Team Joined: Jul 2011 From: Texas Posts: 3,101 Thanks: 1677  

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