I asked a question on English.stackexchange.com but they told me that my question was not about English, and it was rather about math. So, I decided to ask it here 🙁 They closed my thread, so please do not close it here too (I beg you), or at least tell me a website name or somewhere that I can learn 🙁
What do you call the x in the brackets like that:
f(x) = ax² + bx + c
If I am not mistaken, the x in the brackets is called a variable; a, b, and c are called parameters or variables. Am I right?
The x (or any variable or number) in the brackets can also be called an argument, correct?
But what is a variable in mathematics? For example in the function above, can we call x a variable?
In an equation like:
y = ax² + b + c
x and y are variables (I might be wrong). Is it possible that we can call x and y arguments?
Many thanks
Best Answer
Much like programming, you have functions with parameters. You can call these functions and expect an output.
Lets assume we define a function $f$:
$f: \mathbb Z \to \mathbb Z$
meaning we expect this function to spit out integers when it is fed integers.
Lets furtherly narrow it down, and define the function $g$ as:
$g(x) = x-1$
Now we write x-1, using the parameter x, indicating the $x$ is a placeholder for an unknown value.
Lets try feeding a number to our function. $g(1) = (1)-1 = 0$. Thus, we have input of $1$, and output of $0$. So I wrote a function dependant on a parameter, $x$, a constant, $-1$, and called it with $x=1$ as an argument.
Did that clear things up?