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# Function Notation How do you teach function notation? How would you help your students avoid this sort of mistake?

## 3 replies on “Function Notation”

One thing I’ve started is to stop using () in function notation, but to use [] instead (e.g., y = f[x] instead of y = f(x)). Too many students still think it’s about multiplication.

Well, and it looks like the student was evaluating correctly on the right there, they have a j(3) =. They simply wrote their answer also inside the notation. (I’ve seen worse, like when they divide their answer by 3…)

I try to make it clear that the number in brackets next to the function name (“x”) is the x-coordinate we’ll use in the function. The input. The horizontal locator. When you calculate to an answer, that’s the y-coordinate, the vertical part. You need both to describe the final point properly.

Though looking at the table as the page reloads here, yeah, also not correct. Maybe the x-coordinate idea would have clued them in from f(2011)? I don’t know.