From the marker:

In calculus, no 2: most people did not use the chain rule.
So they basically didn't use part 1 to do it.

For the Taylor series, they didn't realize that the 
Taylor series about any number for x^3 is going to give back x^3.  For the
other series, log(1+x) about x=0, a lot of them stopped after the third
derivative.

The idea of closed, open, boundary seemed to cause a lot of problems.

The matrix part was done well.

Summary: Review the calculus and the topology.