How to judge whether the extreme point is a maximum or a minimum in the derivative function Such as the title

How to judge whether the extreme point is a maximum or a minimum in the derivative function Such as the title

If the left derivative value is greater than zero and the right derivative value is less than zero, it increases first and then decreases, and reaches the maximum value;
Conversely, if the left side is less than zero and the right side is greater than zero, it is a minimum
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