Errata for Lecture Notes for Math 181 p. 7 line 5 should read Figure 1.2.1 p. 7 line 9 should read Figure 1.2.2. p. 7 line 10 should read Figure 1.2.2. p. 7 line -8 should read Figure 1.2.2. p. 7 line -2 should read Figure 1.2.1 p. 8 line 5 should read v in terms of u.