At what point does the cubic function attain its local minimum?

Answer and explanation

Correct answer: B.

At : , which is a local maximum.
At : , which is a local minimum. Thus, the local minimum occurs at .
  1. Step 1: Find the first derivative: .
  2. Step 2: Setting gives stationary points at and .
  3. Step 3: Find the second derivative: .
Answer
.
Why not the others: is the local maximum point; is the inflection point where ; is the -intercept.

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