These are pretty basic single input/single output (SISO) systems so a good place to start on these would be your controls book, specifically how to construct and analyze a root locus plot. You can use MATLAB to construct a root locus plot using the rlocus() command from the Control Systems Toolbox.
In response to your PM, here is how to determine the closed-loop transfer function for the first problem. You ought to be able to figure it out on your own from here.
Comments
These are pretty basic single input/single output (SISO) systems so a good place to start on these would be your controls book, specifically how to construct and analyze a root locus plot. You can use MATLAB to construct a root locus plot using the rlocus() command from the Control Systems Toolbox.
Wikimedia has some decent documentation:
http://en.wikibooks.org/wiki/Control_Systems/MATLAB
-drasnor
-drasnor