Is every numerical or algebraic expression a relation?

Question

This may be a simpleton question since I am trying to understand functions and relations. However, every arithmetic operation: addition, subtraction, multiplication and division are defined as 'functions." Well, functions are relations. Does this imply that even in a simple numerical expression such as 2+2 that this is simply a relation between two quantities(function form of a relation)? That is,the input x, being the quantity 2, going through the operation or function of x, namely adding another quantity of 2? In other words F(x)= x+2? Simply put, this would mean that every expression, numerical, algebraic and polynomial would be a relation (not necessarily a function)? It just seems to be true especially when I realized that a rational number is a ratio of two integers, but a ratio is defined as a quantitative relationship between two amounts and shows how many times one value contains or is contained by the other. Thoughts please.

Answer 1

let $f(x)$ be a function, that means for each unique input $x$ we will get unique value of $f(x)$.

But, let $g(x)$ be a relation, then for for each unique input $x$ we may or may not get unique values of $g(x)$.

Conclusion: Every function is a relation but every relation is not necessarily a function.