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+0  
 
 #1
avatar+18754 
+2

My 'stab' at it:

 

Surface area will be the are of the square bottom  PLUS the 4 rectangular sides

 

s = side width and square side

 

square area = s^2

 

h = height of rectngle area   surface area of the 4 sides =  s x h x 4 = 4 sh

 

4sh + s^2  = area

 

Volume = s x h x s = s^2h = 1372  cm^3

 

h = 1372/s^2

 

4 s 1372/s^2 + s^2 = area

5488/s + s^2 = area

s^2 + 5488 (s^-1) = area      Take derivative and set = 0 to find the minimum  (not SURE about this step)

2s - 5488 s^-2 = 0

5488 s^-2 = 2s

5488 = 2 s^3

2744 = s^3     s =  14            and s x h x s = 1372     then h = 7   

 

   surface area then = 14 x14 + 4 x 7 x 14 = 196+4*7*14 = 588  cm^2

 Jul 16, 2019
edited by ElectricPavlov  Jul 16, 2019
edited by ElectricPavlov  Jul 16, 2019
 #2
avatar+102386 
+1

EP is correct!!!!

 

BTW..... we can verify that  s = 14  produces a minimum surface area by taking the derivative  of

 

2s -  5488s^(-2)  =

 

2  + 10976s^(-3)  

 

When s = 14    this is  > 0     which means that s = 14  produces a minimum surface area

 

 

cool cool cool

CPhill  Jul 16, 2019
 #3
avatar+1034 
0

What is the minimum surface area that suc---

 

wat?

 

Is it just me or Do i not get it...

 Jul 16, 2019

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