What is the correct order of operations for differentiating r^2 with 2/r*d/dr?

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SUMMARY

The correct order of operations for differentiating the expression \( \frac{2}{r} \frac{d}{dr}(r^2) \) is to first apply the differentiation operator to \( r^2 \) and then multiply the result by \( \frac{2}{r} \). This is confirmed by the equation \( \left( \frac{2}{r} \frac{d}{dr} \right)(r^2) = \frac{2}{r} \left( \frac{d}{dr} r^2 \right) \), which demonstrates that the differentiation must precede the multiplication. The confusion arises when the operations are not clearly delineated, leading to different results if performed in the incorrect order.

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timmo567
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as an example, say I am operating on r^2 with 2/r*d/dr :

do I differentiate r^2 first, then times by 2/r or times by 2/r and then differentiate. Confused as they give different answers
 
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The operator works precisely as you would expect when you write it out. So
[tex]\left( \frac{2}{r} \frac{d}{dr} \right)(r^2) = \frac{2}{r} \left( \frac{d}{dr} r^2 \right).[/tex]
 

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