Sept. 10 Class

Learning Goals: Understand function notation.

Today I discussed how to describe functions using function notation.  The symbol:

f(x) 

is what we use to denote a function.  The f is the name of the function, the brackets indicate what the input should be.  If we input an x value, what the function gives us is the corresponding y value.  Therefore, this symbol is also used in place of the y in an equation:

y = f(x)

From now on, when we look at the equation of a function, we use f(x) instead of y.

Example:  Given the function f(x) = {(1, 2), (3, 5), (4, 6)}, what is the value of f(3)?

Solution: f(3) = 5.

This tells us that when x is 3, y is 5.

Example: Use the given graph to evaluate f(3) and f(-1).

Solution: Looking at the graph, when x = 3, we have y = 4.  Therefore the solution is:

f(3) = 4

Also from the graph, when x = -1, we have y = 0.  Therefore, the solution is:

f(-1) = 0

Example: For the function f(x) = 6x + 3, what is f(1/2)?

Solution: We substitute in 1/2 in place of x.

The solution is f(1/2) = 6.

Homework: 

P. 25 #10

P. 32 #1-9, 10v, vi, 11v, vi, 12-15