Domain/Function Notation/Symmetry...

Please help! I hit a snag while attempting these, and will try to explain why, but it might just be easier to compare my answer to others. And I dont know how to do symbols so I will try to explain it. Thanks!

Find the domain of the following function...

n(x)=

The square root of (2-3x) over 3x+1

got the 2 domains but not sure if I can have a negative part? since its a square root..

For the function f(x)=square root of x^2-2x, g(x)= 2 over x^2-4, find:

g [f(2)]

For the following functions, determine whether their graphs are symmetric about y-axis, origin, or neither:

f(x)= -4 over x^3

okay last one sorry!..

so theres a graph and it is asking for zeros of f. (how do I write that? just how many times it hits the x axis? or what those points are) and intervals where f is increasing, decreasing or constant. and I just don't know how I would write that answer either. and last but not last it wants to know the intervals where f is positive, and where it is negative. is it negative only when under the x axis? or for it to be positive does it hvae to be in the 1st quadrant of the graph?

thanks in advance for any help!!!