Graphing functions is an easy task on a graphing calculator. You simply press and enter the function you wish to graph.
Remember that f(x) is simply the function notation to represent a y–value. So the two expressions y = 2x + 7 and f(x) = 2x + 7 are just different ways to write the same thing and will produce the same graph. So whether your function is given as f(x)= or y=, you still press the key to enter the function.
To get x to appear on the screen, use the key.
As long as your function is not very complicated, you should be able to see the graph in a standard viewing window
You can enter this by hand or press . To learn more about the key, click here for information on the WINDOW keys.
Sometimes you will see function expressed with different names and different variables. For example, the function g(r) = 2r + 7 has the same graph as the one above. The name of the function is g and the variable in the function is r. You still press the key and . When graphing functions, it doesn’t matter what name the function has or what the variable used is, the calculator can only accept something as Y= and only with the variable of x.
Another common way to name a function and a variable is s(t) = 2t + 7. The name of the function is s and the variable in the function is t. Again, to graph this function, you press and .
Although the variables in the last two examples have been r and t, the expression still asked you to choose a value for y or x and then produce the function value to go with it. The graphs are all the same no matter what the name.
Usually, functions expressed as s(t) are representing the position of an object. Just remember that when you see a function in this form, you can still graph it using the key and the key.
Try graphing the functions below. You may need to change your window setting for some of these. If you need help doing that, click here to go to the
window lesson. Example #1: y = 3x  2Example #2: y = x + 1Example #3: f(x) = 7x^{2} + 3x  1Example #4: g(x) = (1/3)x Remember to be careful with the fraction and parentheses. Example #5: s(t) = 16t^{2} + 75t +80Example #6: s(t) = 4.9t^{2} + 20t + 30
In order to get the graph shown here, I used the following window setting.



