Answer: x = 5
Explanation: To find the where the absolute minimum of f occurs from f', we can find where f' changes from negative to positive.
Think about it this way: an absolute minimum on f would look like a "U", meaning that the function would decrease and then increase. In other words, the slope would change from negative to positive.
So, if we find where f' changes from negative to positive, we can find where the absolute minimum occurs. The only x-value where this occurs on f' is x = 5.