This is real easy. No calculating required, just look and see.
Determine whether the relation is a function.
{(-5, -4), (-2, 9), (-1, -2), (-1, 7)}
This is NOT a function because (-1, -2) and (-1, 7) are two different
ordered pairs with the same FIRST coordinate -1. A function cannot
contain two different ordered pairs with the same FIRST coordinate.
Determine whether the relation is a function.
{(-7, -1), (-7, 2), (-1, 8), (3, 3), (10, -7)}
This is NOT a function because (-7, -1) and (-7, 2) are two different
ordered pairs with the same FIRST coordinate -7. A function cannot
contain two different ordered pairs with the same FIRST coordinate.
Determine whether the relation is a function.
{(1, -3), (1, 1), (6, -8), (9, -3), (11, -3)}
This is NOT a function because (1, -3) and (1, 1) are two different
ordered pairs with the same FIRST coordinate 1. A function cannot
contain two different ordered pairs with the same FIRST coordinate.
Determine whether the relation is a function.
{(-6, -9), (-2, 1), (1, -1), (7, -7)}
This IS a function because it does NOT contain two different ordered
pairs with the same FIRST coordinates.
[Note that a function may contain two different ordered pairs with the
same SECOND coordinates. It's only the FIRST coordinates that cannot
appear twice in two different ordered pairs.]
Edwin