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Tha Wishkah

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seem to be having a mental blank atm in my revison:

Question: a rectangular prism with square base has surface area = 250cm^2
a) Show volume
V= (125x - x^3 )
. . . . . 2

I can do this, but then
b) Find dimensions to give max volume.

I know you've got to differentiate the above equation for V, but i always find V' to be the same as V, so i'm doing something wrong and can't figure out what =\
 

Timothy.Siu

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V= (125x - x^3 )
. . . . . 2

v'= (125-3x^2)/2
so 3x^2=125
x^2=125/3
x=root(125/3)
? looks wrong
 

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