If , what is the derivative ?

Answer and explanation

Correct answer: A.

  1. Step 1: Apply the chain rule: .
  2. Step 2: Here , so and .
  3. Step 3: Thus .
Answer
.
Why not the others: The option without 2 in the numerator forgets the inner chain rule derivative; the rational form without radical represents the derivative of arctan; and squares as instead of .

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