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jmc

algebra senior

Problem

The graphs of and are drawn. For every , a vertical segment connecting these two graphs can be drawn as well. Find the smallest possible length of one of these vertical segments.
Solution
The function is difficult to deal with directly. Instead we work by cases: and .

If then , and we can find the difference by subtracting This function is always increasing as varies over the nonnegative numbers, so this is minimized at . The minimum value on is If then and we can find the difference by subtracting: This quadratic is minimized at , and the minimum value is Since the minimum value on negative numbers is less than the minimum value on the nonnegative numbers, the minimum value for the difference is .
Final answer
1