title: What exactly does f: R->R or f:Z->R mean in discrete math?
body: <p>I came across a topic that I'm not too familiar with. It asks for whether a certain function f(x)=1/(x^2-2) defines a function f: R->R and f:Z->R.</p>
  
  <p>What is the question asking for? The topic is discrete mathematics.</p>