Difference between revisions of "2010 AMC 12A Problems/Problem 22"
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Revision as of 17:36, 12 February 2010
Problem 22
What is the minimum value of ?
Solution
If we graph each term separately, we will notice that all of the zeros occur at , where is any integer from to , inclusive.
The minimum value occurs where the sum of the slopes is at a minimum, since it is easy to see that the value will be increasing on either side. That means the minimum must happen at some .
The sum of the slope at is
Now we want to minimize . The zeros occur at and , which means the slope is where .
We can now verify that both and yield .