1. The problem statement, all variables and given/known data Show that |a-b|<= |y-a|+|x-y|+|x-b|, for all x,y in ℝ 2. Relevant equations 3. The attempt at a solution |a-b| <= |y-a+x-y+x-b| (correct? Not sure about this one...is it not part of the triangle rule?) |a-b| <= |2x-b-1| |a-b+2x-2x| <= |2x-b-1| |a-2x| + |2x-b| <= |2x-b-1| really have clue what I am doing here, no idea if I am on the right track...doubt it is right. Please help. Thanks!