Solution to Homeowrk Sec 2.2, page 63 ______________________________________________________________ #9. Show lim as z -> -i of 1/z is i. Pf. |1/z - i| = |1/z + 1/i|, since 1/i = -i = |z+i| / |z|, after getting a common denominator. Now, |z - (-i)| < delta => 1 - |z| < delta, since by the triangle inequality |A| - |B| \leq |A - B| \leq |A| + |B|, where \leq means "less than or equal to." => |z| > 1-delta, after solving the last inequality for |z| => 1 / |z| < 1 / (1-delta), by taking reciprocals. Thus, |1/z - i| < delta/(1-delta). Therefore, if we choose delta = epsilon/(1+epsilon) we are done. ___________________________________________________________________ #12. This problem was done in class. Refer to your lecture notes for details. ___________________________________________________________________