+0  
 
0
28
4
avatar+622 

i have already completed the question im just using this as an example

For question c i found f'(x) then i found the value of x via simple algebra manipulation 

but what if the question asks for the maxmimum value of P??

 Jan 8, 2019
 #1
avatar+15350 
+1

If you have the value of 'x' that minimizes P......   Sub that value in to the equation for P to find the minumum value of P.

 Jan 8, 2019
 #2
avatar+622 
+1

do you mean the maximum value of P?

YEEEEEET  Jan 8, 2019
 #3
avatar+15350 
+1

Your question asks for the MINIMUM value of P........      There likely is no MAXIMUM value of P....you can make the perimetr as large as you want.

ElectricPavlov  Jan 8, 2019
 #4
avatar+94526 
+1

P = 100x^(-1)  + x ( pi + 8 - 2sqrt(3)/ 4      take the derivative, set to 0

 

P'   =   -100x^(-2)  +  ( pi + 8 - 2sqrt (3) ) / 4   = 0       multiply through by x^2

 

[ ( pi + 8 - 2sqrt (3)  / 4   ] x^2  - 100  =  0

 

[ pi + 8 - 2sqrt (3) ] x^2  =  400 

 

x^2 =   400 / [ pi + 8 - 2sqrt (3) ]       take the positive root

 

x =  7.218

 

Sub this back into P  to find the minimum P  ≈  27. 7  m

 

We can verify that this is the minimum ........

 

P "  =  200/ x^3 

Subbing in  x = 7.218   will produce a positive....thus...x = 7.218 produces a minimum value

 

 

cool cool cool

 Jan 8, 2019

25 Online Users

avatar
avatar

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.