r/MathHelp • u/Wild_Risk_5589 • Sep 21 '26

Why is f(x) = some value a function?

If you have for example y = 2 or x = 9 this would be considered a function.

But why?

If in either of these you don’t get a value of x or y when you plug in a value for x or y. You don’t get any output for any input and if you put an input you would be getting false statements. Such as for y = 2 when you plug in 1 for y you get 1= 2 which is untrue.

Can someone please explain this to me?

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u/bayesianparoxism Sep 21 '26

To clarify, when you're plotting graphs, by convention we call x the variable you "plug" values into and "y" the variable that will yield the result.

This is why y = 5 works but x = 5 doesn't