Graph the equation on the calculator, and look for the behavior of the graph. If the graph is 1/x, for instance, it will go to 0 if x goes to positive infinity (look at the x-axis and pretend that you're going to the right of the x-axis).

When you say 1+ or 1- are you referring to positive 1 and negative 1 or "as x goes to 1 from the left or right side?"