Calculate the points you need to plot by inputting several values of "x" into the function and solving for "y." For example, find the "y" values for your function of the following values of "x": -2, -1, 0, 1 and 2. If the function in question is y = x^2, the values are as follows:
y = (-2)^2 = 4 = (-2, 4)
y = (-1)^2 = 1 = (-1, 1)
y = (0)^2 = 0 = (0, 0)
y = (1)^2 = 1 (1, 1)
y = (2)^2 = 4 (2, 4)
Draw an x-axis and a y-axis on your graph paper if they don't already exist, setting the point where the horizontal and vertical lines cross as "(0, 0)." Plot the points you calculated onto the graph and connect the dots to form lines or curves.
Examine the graph to determine the maximum and minimum values of "x" and "y" -- the "domain" and "range," respectively. For y = x^2, the "x" values extend infinitely in both the positive and negative directions; whereas the minimum "y" value is zero and the maximum is infinity. The domain of the function, therefore, is "all real numbers," while the range is "y ≥ 0" -- "y" is greater than, or equal to, zero.