Find the solution set for |a-1| + |a-2| + |a-3| ā„ 6.
Establish the following vector inequalities geometrically or otherwise:
(a) |a + b| ā¤ |a| + |b|
(b) |a + b| ā„ ||a| ā |b||
(c) |a ā b| ā¤ |a| + |b|
(d) |a ā b| ā„ ||a| ā |b||
When does the equality sign above apply?