9/12 Lecture: Contour lines for x2+y, Graph of x2+y,
Contour lines for x2+y2, +y, Graph of for x2+y2,
Contour lines for (x-y)/(x+y), Graph of (x-y)/(x+y),

9/23 Lecture: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

9/30 Lecture: 1 2 3 4 5 6 7

10/12 Lecture: 1 2 3