Example 1: Is {(6, −3), (4, 1), (7, −2), (−3, 1)} a function? Is its inverse a function?

Since each element of the domain is paired with exactly one element of the range, the relation is a function.

However, its inverse is not a function since 1 is paired with more than one element of the range: the values of 4 and −3

inverse: {(−3, 6), (1, 4), (−2, 7), (1, −3)}

The equation y = 2x + 1 can be written as f(x) = 2x + 1.

If x = 3, then f(3) = 2(3) + 1 , or 7.

Thus, f(3), which is read "f of 3," is a way of referring to the value of y that corresponds to x = 3.

Example 2: If f(x) = 3x −4, find f(3) and f(−2)

Directions: Determine whether each relation is a function.

yes, yes, no

yes, no, yes

yes, no, yes

4, −4, −14, 21, −⁷/₂ , −¹⁵/₁₆