MATH 125 Study Guide - Midterm Guide: Identity Element, Triangle Inequality
Document Summary
The symbol r denotes the set of all real numbers. R is equipped with the familiar operations of addition (de- noted +) and multiplication (denoted , though we usually just write ab instead of a b). A more subtle feature of the real number system is the no- tion of positivity, and the existence of the absolute value operation: recall that, for any a r, we set. A if a 0 if a < 0 (i. e. , |a| = a2) If we think of r as an in nite straight line, then we can regard. |a| as giving the distance from a to 0 . Triangle inequality: |a + b| |a| + |b|. 1 the geometry and algebra of vectors. We distinguish between two types of physical quantities: scalars: possess quality of magnitude only, vectors: possess qualities of magnitude and direction. Example: in physics, speed is understood as a scalar quan- tity, while velocity is a vector quantity.
