Function Machine (with substitution of values shown)
1) Input a value for x at the top of the machine and watch the machine produce the output.
Try a few different values of x.
2) Change the function's expression by typing in the white input box at the front of the machine, or use preset functions in the drop down list as shown.
Repeat step 1)
A function's output depends on the input value and the function's algebraic expression!
See an alternative function machine that processes patterns, numbers and simple equations.
https://phet.colorado.edu/sims/html/function-builder/latest/function-builder_en.html