Linear Sentences in One Variable
Relations and Functions
An equation involving x and y and which is also a function can be written in the form y = “some expression involving x”; that is, y = f ( x). This last expression is read as “ y equals f of x” and means that y is a function of x.
If
y = 4
x + 3, then
f (
x) = 4
x + 3. The question “What is
y when
x = 2?” would be expressed as “What is
f (2)?” if
|
then
|
The statement f (2) = 11 says, “When x equals 2, y equals 11”; that is, the ordered pair (2, 11) belongs to this function.
Example 1: If f ( x) = x2 + 2 x + 3, find each of the following.
