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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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    In your first equation, what is the "?" supposed to represent? I think if you replace that with the correct derivative of V(x), you'll be able to find your answer. Just to be clear: write the equation for the volume of a cube with side length x, then take the derivative of that equation, then plug in 4.2012-10-22
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    an unknown number2012-10-22
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    I don't have an equation.2012-10-22
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    Try searching the internet or your calculus book for equation for the volume of a cube.2012-10-22
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    $x * x * x$ right?2012-10-22
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    Can you write x times x times x in a simpler form? What shorthand notation do we have for multiplying something by itself several times?2012-10-22
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    Oh I get it $x^3$ and the derivative of that would be $3x^2$2012-10-22
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    So the answer would be 48. Thank you!!!2012-10-22

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