Which relations are functions? select each correct answer. explain how you know.

A relationship between two values can be called a function if every input value produces exactly one output value - in other words, if a function  takes in some number  as input, every value of  will produce a single value  as its output. Multiple  values might produce the same , but no one  value will produce more than one  value.

Here, we can see that the graphs b) and d) capture this kind of relationship, as each value on the  axis is associated with one unique point on the graph. a) interestly enough, can be thought of a function, too; if we describe  as a function of , then every  value produces exactly one  value. The relationship captured in c) can't be interpreted as a function in either direction, though.

I assume this question is asking for  as a function of  though, in which case options b) and d) will be the correct response.