The expression y = 2 represents a function. In this case, it is a constant function, where the output value of y will always be 2, regardless of the input value of x.
To determine if an expression defines a function, we need to check if each input corresponds to exactly one output. In this example, for any value of x that we choose, the output will be y = 2. This means that for any x, the relationship is clear and consistent, fulfilling the definition of a function.
Furthermore, if we were to graph this expression, it would be a horizontal line on the coordinate plane at the height of 2. Since every point on this line corresponds to a unique input with the same output, this reinforces the fact that y = 2 is indeed a function.