Question

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Answer 1

two different operations? like addition and multiplication?

Answer 2

how about \[f(x)=2x+1\] that has both

Answer 3

if you took a certain number, and you doubled it, would you get more than one result?

Answer 4

if you don't like it, use another one
there are an infinite number to choose form
for example \[f(x)=\frac{1}{x}\] or \[f(x)=x^2+x\] or any you like

Answer 5

f(x) = 2x+1 is a valid legitimate function

A function is just a rule that assigns one number (input) to another number (output)

The function rule for `2x+1` is: double the input, then add 1 to get the output

Answer 6

anything that involves arithmetic is usually a function

examples:
f(x) = x+2
f(x) = x*4
f(x) = x^2 - 3x