Common Calculus Mistakes
Product Rule: Constants

The Goal

Find

goal


The Mistake

Find the mistake:

mistake

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The Correction

correction

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An Explanation

In the second factor the constant 200 has derivative 0, but the student left the 200 in place, perhaps distracted by differentiating the following term (1/2)r2π.

This derivative is easier to compute by multiplying out the expression to be differentiated first and then taking the derivative without using the product rule.

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