October 30th, 2008, 02:40 AM  #1 
Newbie Joined: Oct 2008 Posts: 14 Thanks: 0  Minimum value
I am very green around the gills with calculus and i have this question that i have to find the number of (x) that's needs to be produced to minimize the cost of P I am given P(x) = 2x^35x^2+2 dy/dx = 6x^210x 0 = 6x^210x 10x = 6x^2 10 = 6x x=10/6 = 5/3 P = 2*(5/3)^3  5*(5/3)^2 + 2 p = 2.6296 d2y/dx2 = 12x10 =12*2.629610 =41.55 This is where i get stuck i have checked x and P on graphmatica and i can see where they are but not sure what to do with them now. Can anyone help me .... 
October 30th, 2008, 05:49 AM  #2  
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Minimum value Quote:
 
October 30th, 2008, 06:33 AM  #3 
Senior Member Joined: May 2007 Posts: 402 Thanks: 0  Re: Minimum value
The second derivative check is used to see if the x obtained by solving f'(x)=0 is a minimum or a maximum (or none). It is necessary to check this since the problem specifies to find the minimum value of x, not the x where the derivation of P equals 0  that is just a way of solving it.

October 30th, 2008, 12:18 PM  #4  
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Minimum value Quote:
 
October 30th, 2008, 01:56 PM  #5 
Newbie Joined: Oct 2008 Posts: 14 Thanks: 0  Re: Minimum value
Thanks for all your help i will go back and have a look at what you have said

October 30th, 2008, 05:09 PM  #6  
Senior Member Joined: Mar 2007 Posts: 428 Thanks: 0  Re: Minimum value Quote:
 

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