Link to test: http://www.math.ucla.edu/~cmarshak/GRE2.pdf

#18 - I figure this ultimately comes down to knowing power series expansions for some common mathematical expressions, but I am weak in this area. How would you approach this? What should I brush up on? Please explain it like I'm 5.

#19 - "Which of the following is a general solution of the differential equation:

y''' - 3y'' + 3y' - y = 0

And then each option is a bunch of e^t terms.

This is a type of problem where I'd probably waste a lot of time trying to find the derivatives and plugging things together. It's easy to make a mistake going that route. Are there any facts or approaches to this problem which make it less mechanical or more obvious what *isnt* the answer?

Thanks!