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Sodium chlorate crystals are easy to grow in the shape of cubes by allowing a solution of water and sodium chlorate to evaporate slowly. If $V$ is the volume of such a cube with side length $x$, calculate the derivative when $x = 4 \text{ mm}$.

$V'(4) = \cdots \text{ mm}^3/\text{mm}$

I thought that:

$V'(4) = 64 \text{ mm}^3/\text{mm}$

Because volume of a cube $=$ $4 \times 4 \times 4$

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    So the answer would be 48. Thank you!!!2012-10-22

1 Answers 1

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$V(x)=x^3$ is the volume of a cube with side $x$. Take the derivative of that to get $V'(x)$ and then calculate $V'(4)$.