Answer:
Explanation:
A function is a relation (a set of ordered pairs) with the additional property that: no two pairs have the same first element and different second elements.
The definition is often stated as: A relation in which every
x
value is associated with exactly one
y
value. "Exactly one means one but two or more:
{(1,2);(2,3);(3,4);2,5)}
includes the points
(2,3) and (2,5)
. Therefore this set of pairse is not a function.
Note
{(0,1),(1,3),(2,5),(3,5)}
is a function.
(It is ok to have different first elements and the same second elements. The definition of function is very precise.)
