It sounds like you are running this in the kernel and not the front end. How did you launch Mathematica?

Run Mathematica, rather than Wolfram.  In the Wolfram language, graphics have to be exported to be viewed.

Well, in linux, you can launch the front end with the command mathematica. I'm not entirely sure, but I think the command is the same on Mac (I always use the icon in that bar at the bottom) and I always just use the start menu item in Windows. If you're using a unix based system, a front end does requires some form of X-win. 

The front end was separated from the kernel a long time ago so that you could run computations and still have a responsive Mathematica running, in case you wanted to quit the computation or any number of other things. Most people use the front end and run a notebook, which has a graphical interface. In that form, it's kind of a graphical interactive computational engine as opposed to something terminal-like which is how the kernel runs. When you use a command like Plot, the front end sends the command to the kernel which commputes what the result should be. That result is then sent to the front end which takes the result and creates the actual graphics. Plot is one of many functions that requires a front end to execute. 

Hi Luther,

I do not know what in this case % is standing for,
but maybe you should try to plot f rather f(x).

Henrik

Hi and thanks for following through. First, the % refers to a differentiation of a messy algebraic function in the preceding action. 

Once it became clear what the "front end" was, I was able to plot my function.

Thanks for your interest and contributions. Sooner or later I tend to get it.

Luther