What is the domain of this function 9 2 2 10 5 9 4 5?

Okay, so someone’s asking about the domain of a function… and they give us these numbers: 9 2 2 10 5 9 4 5. Right off the bat, looks like they’re giving us some points, right?

Basically, the domain? That’s just a fancy word for all the possible “x” values you can plug into a function. Think of it like this: if you’re feeding numbers into a machine (the function), the domain is all the stuff you’re allowed to feed it. Makes sense, right?

Okay, so they give us these points: (9, -2), (-2, -10), (5, -9), and (4, 5). I mean, sometimes they give you these problems in a list, sometimes they give you the points visually on a graph. It’s all the same in the end.

So what’s the domain then? Well, we just pluck out all the first numbers in each pair. Because those are the x-values! So we got 9, -2, 5, and 4.

Therefore, the domain of this particular function (well, the part they showed us anyway!) is simply {9, -2, 5, 4}. And that’s it. Sorted! I mean, it looks complicated at first, but when you break it down, it’s actually pretty straightforward, wouldn’t you say?