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December 11th, 2012, 04:46 PM  #1 
Senior Member Joined: Mar 2012 Posts: 111 Thanks: 0  Dimensions of max area and area itself?
so far i got: y = 49x^2 Area = 2x(49x^2) Area = 98x  2x^3 6x^2 = 98 x^2 = sqrt(98/6) === 2sqrt(7)/(sqrt(6) 
December 11th, 2012, 06:11 PM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  Re: Dimensions of max area and area itself?
You have the correct area function: Differentiating and equating to zero, we find: So, our critical number is found from: Taking the positive root, we find: and so: To ensure we have a maximum, observe that: , and since our critical number is positive, the second derivative is negative, showing we do have a maximum. Hence: 
December 11th, 2012, 06:13 PM  #3 
Senior Member Joined: Mar 2012 Posts: 111 Thanks: 0  Re: Dimensions of max area and area itself?
thanks mark! 

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