Answer:All of the examples define relations between a domain and range.Such a relation will be a function if and only if each value in the domain corresponds to at most one value in the range.In the first example, the value −1 in the domain is associated with two values in the range, namely −5 and 1 .In the second example, the value −1 in the domain is associated with two values in the range, namely 7 and 1 .In the third example, the value 3 in the domain is associated with two values in the range, namely 2 and 4 .In the fourth example, each of the values in the domain is associated with one value in the range, so this describes a function. Note however that the values −4 and −7 are both mapped to 5 . So the function described is not one to one and consequently its inverse is not a function.