how do i graph y = f(x/3) on my calculator?

Answer 1

Enter the formula for f(x) then edit it by changing x to x/3 everywhere.

If all you want to know is the shape of the graph, f(x/3) is the same shape as f(x). It is just stretched in the x-axis direction.

Answer 2

Press the [Y=] button

In Y1 put your f(x) function.

In Y2 type [VARS]
Go to Y-VARS, Function, Y1, Now type (X/3)
In Y2 it should read
Y1(X/3)

Now your Y2 values will take the function of Y1 but with X/3 as your x value.