Which relation is a function? A. {(–3, 4), (–2, 5), (0, 9), (0, 12)} B. {(1, 2), (1, 5), (1, –1), (1, 4)} C. {(8, –1), (2, –1), (3, 8), (2, 5} D. {(7, 12), (1, –5), (3, –10), (2, –5)}

Question

Which relation is a function?	    A. {(–3, 4), (–2, 5), (0, 9), (0, 12)}    B. {(1, 2), (1, 5), (1, –1), (1, 4)}    C. {(8, –1), (2, –1), (3, 8), (2, 5}    D. {(7, 12), (1, –5), (3, –10), (2, –5)}

anonymous · Answer

please explain, i don't understand.

zzr0ck3r · Answer

A function is a binary relation in which every element of the domain (the x values) are connected with at least one of the y values (the range), and that if the x value is any two pairs are the same, then so must be there y values, 

notice the first part is taken care of in all of the relations because they are all in pairs, so every x value is with some y value

so you need to make sure that you have no pairs that have the same x values but different y values

example: if some relation contains the pairs (2,3) and (2,5) then it would not be a function. So which relation does this not happen in?