In mathematics, value commonly refers to the 'output' of a
function. In the most basic case, that of unary, single-valued functions, there is one input (the argument) and one output (the value of the function).Example: If the function is defined by prescribing that for each real number , then the input 3 will yield the function value 10 (since indeed ). The function of the example is
real-valued, since each and every possible function value is real. On the other hand, it is not
injective, since different inputs may yield the same value; e.g., , too.
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