Page 163 - Algebra 1

Identifying a Graph as a Function
Use the table. Graph the ordered pairs on a coordinate grid and determine whether the ordered pairs represent a function.
SOLUTION
No matter what vertical line is drawn, the graph is intersected at only one point by each line. The ordered pairs represent a function.
In a function, the independent variable determines the value of the dependent variable. This means the dependent variable y is a function of the independent variable x. In terms of the variables, y is a function of x and can be written like the following example:
y = f(x)
y = 6x + 3 f(x) = 6x + 3
Writing a Function
a. Write x + 2y = 5 in function form. SOLUTION
x + 2y = 5
Example
3
Hint
More than one vertical line should be drawn along the x-axis to check using the vertical-line test.
Domain (x)
Range ( y)
-6
-4
0
-1
2
0
5
_3 2
7
_5 2
4
x
-8
-4
4
8
-4
-8
Reading Math
f(x) is read as “f of x.”
Example
4
148 Saxon Algebra 1
b.
Food labels list the grams of fats, carbohydrates, and proteins in a single serving. Proteins convert to 4 calories per gram. Write a rule in function notation to represent the number of calories from protein.
y=-_x +_5 22
f ( x ) = - _x + _5 22
Solvefory.
8
y
SOLUTION
The number of calories depends on the number of grams of protein eaten. dependent variable: number of calories
independent variable: number of grams of protein
Let p represent the number of grams of protein. y = 4p
f(p) = 4p Use function notation.