I'm confused about how to use derivatives, now that we have learned so many rules.

My question is, find each derivative. Leave the answer as is.

a) f(x) = (x^2)^1/3 (to the third root)

b) f(x) = (x^2 + 3)/(2x - 1)

c) f(x) = [ (x^2 - 1)^4 ] * [ (2x + 1)^3 ]

d) f(x) = [ (2x + Sqrt (x^4 - 2x + 1)]^7

I'm confused by when to use the rules so as of now, I don't really know where to start?