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Volume of a cube versus side length 
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#1
Apr1408, 06:38 PM

P: 42

Show that the rate of change of the volume of a cube with respect to its edge length is equal to half the surface area of a cube.
I know that surface area= 6l^2(because of the six faces) I know that volume is l^3. How do I relate volume then to edge length 


#2
Apr1408, 07:19 PM

P: 587

The "rate of change" is the derivative. So what is the derivative of the volume with respect to the edge length? 


#3
Apr1408, 07:21 PM

P: 42

Thanks! I now realize that the first derivative of the volume is 3l^2, which is half the surface area



#4
Apr1408, 07:24 PM

P: 587

Volume of a cube versus side length
Right.



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