# Extra credit

I'll post extra credit problems here occasionally. I have two goals for these:
1. To give problems that are (I hope) interesting and somewhat off the beaten path for this course, but which might be a little too difficult to assign as required homework, or involve something like a computer algebra system which I don't want to require. They'll usually have multiple parts, some harder than others, but you can still get some credit even if you don't do the whole problem.

2. To give problems that involve writing. Explaining something always helps you understand it better. This is especially important for problems which are not entirely computation: there, the explanation is the solution! So, I will be grading your writing. This doesn't mean taking off points for spelling, but rather that if you write down an equation, or claim that X is true, then you should justify/explain it, with honest English sentences. Don't write a solution that will show me you can solve the problem, write one that will show someone who doesn't know how to solve the problem how to solve the problem.

Of course, not absolutely everything needs an explanation: certainly you don't need to write anything when going from x+y = 1 to x = 1-y. In general, it's fine to leave a routine step in a computation that everyone knew how to do coming in to the class without comment. On the other hand, if, say, you convert a triple integral to spherical coordinates, you should say so explicitly; if you use Green's theorem to show [some integral] = [some other integral], then say something like "By Green's Theorem, [some integral] = [some other integral]".