In mathematics, a function is an equation or expression that takes an input and produces an output. The input is typically a number, and the output is typically a number as well. However, functions can also produce non-numeric outputs such as a boolean.

A function’s range is the set of all possible values of its output. For example, the function f(x)=x² has a range of all non-negative numbers (since the output of squaring any number is always a non-negative number). In this case, the range of the function is {y|y ≥ 0}.

Now, the question at hand is which function has a range of y < 3? To answer this question we need to look at the definition of range, and consider which functions can produce an output of 3 or less.

One example of a function with a range of y < 3 is f(x) = 3 – x². This function takes a number as input and produces an output that is 3 minus the square of the input. This means that the output can never be greater than 3.

Another example of a function with a range of y < 3 is f(x) = x + 3. This function takes a number as input and produces an output that is 3 more than the input. This means that the output can never be greater than 3.

In fact, any function of the form f(x) = m – x², where m is a real number, will have a range of y < 3. This is because the output of this function will always be m minus the square of the input, which can never be greater than m.

So, the answer to the question of which function has a range of y < 3 is any function of the form f(x) = m – x², where m is a real number.