In solving a problem, you may assume and use every result and problem which appears before it in the Notes. You are also encouraged to seek help with the homework from either the instructor or the TA.

Optional problems are exactly what the words say: you do not have to hand them in and they will not be taken into account in computing your basic grade for the class. Work on them if they catch your interest, and do not hesitate to ask for help with them if you need it.

**HW #7, due Fri March 17, in class**. x4F.1, x4F.2, x4F.3, x4F.6, x4F.8. Solutions.

**HW #6, due Tues Feb 28**. x4B.5, x4B.7, x4B.9, x4B.10, x4B.11. Solutions.

**HW #5, due Tues Feb 21**. x4A.1, x4A.2, x4A.3, x4B.3, x4B.4, x4B.6. Solutions (now complete).

**HW #4, due Tues Feb 14**. x3B.1, x3B.3, x3B.4, x3B.5, x3B.8. Solutions.

**HW #3, due Tues Jan 31**. x1C.3, x1C.6, x1C.9, x2A.2, x2A.7.

**Optional**. x2A.3, x2A.9. Solutions.

**HW #2, due Tues Jan 24**. x1B.1, x1B.2, x1B.3, x1B.9, x1B.12, x1B.16.

**Optional**: x1B.17, x1B.26. Solutions.

**HW #1, due Tues Jan 17**. x1A.3, x1A.5, x1A.6, x1A.8, x1A.9, x1A.10. Solutions.