The minimum of |x-a1|+|x-a2|+...+|x-an| (where a1<a2<...<an) is achieved at the median of {a1,...,an}. For n=2: min of |x-a|+|x-b| = |b-a|, achieved for all x in [a,b]. For n=3: min at x=a2 (the middle value). For n=4: min at any x in [a2,a3]. This is a powerful technique for optimization MCQs.