Question

Which of the following relations is a function? A.{ (-2, 4), (-1, 3), (5, 2), (1, 4) } B.{ (1, 7), (1, 8), (2, 7), (3, 8) } C.{ (2, 4), (4, 6), (4, 8), (6, 4) } D.{ (5, 7), (6, 3), (8, 6), (5, 4) }

Answer 1

from the pairs of x,y, if the set has two "x" of the same value, that is, "x" repeats, or an x-repeat, then is NOT a function

so, the group that doesn't have any x-repeats, is a function, now let's check


`\bf A.\{ (-2, 4), (-1, 3), (5, 2), (1, 4) \}\\\\ B.\{ (\boxed{1}, 7), (\boxed{1}, 8), (2, 7), (3, 8) \}\impliedby \textit{has one re}\textit{peat, no dice}\\\\ C.\{ (2, 4), (\boxed{4}, 6), (\boxed{4}, 8), (6, 4) \}\impliedby \textit{also has one re}\textit{peat, no dice}\\\\ D.\{ (\boxed{5}, 7), (6, 3), (8, 6), (\boxed{5}, 4) \}\impliedby \textit{same, has one re}\textit{peat, no dice}`