This is a function.
Work Step by Step
A function is a correspondence between a first set, called the domain, and a second set, called the range, such that EACH member of the domain corresponds to EXACTLY ONE member of the range. --- Keywords are emphasized. We see from the graphical definition of the function that EACH input from the domain has an arrow pointing from it to a value in the range. and only ONE arrow originates from each member of the domain. This is a function. NOTE: A misconception that some people have is that, because there are two incoming arrows into 2, they conclude that this is not a function. But, f(a)=2, a is awarded one and only one value from the range. f(b)=2, b is awarded one and only one value from the range. No problems here, this is a function.