Final answer:
The given relation is not a function because the input '11' is associated with two different outputs, '4' and '-6', which violates the definition of a function.
Step-by-step explanation:
The question asks whether the relation { (11, 4), (0, 5), (11, -6), (-5, 8) } is a function. To determine if a relation is a function, each input value (or x-coordinate) must be associated with exactly one output value (or y-coordinate). In this case, the input value '11' is associated with two different output values '4' and '-6', which means that the same input gives two different outputs. Therefore, the given relation is not a function.