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Function Notation

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.









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