Easy Algebra Step-by-Step

Basic Function Concepts 203

Problem Establish a functional relationship between the radius of a

circle and its area.

Solution

Step 1. The formula for the area of a circle is πr^2 , where r is the radius.

Area = A = πr^2

Step 2. Express the area of a circle as a function of its radius.

A(r) = πr^2

Problem Establish a functional relationship between the x and y values

in the following table.

x 34 5 6 7

y 79 11 13 15

Solution

Step 1. Look for a pattern that will connect the two numbers and describe

the pattern in words.

The y number is twice the x number plus 1.

Step 2. Write the pattern for y in terms of x.

y = 2 x + 1

Exercise 19

1. Determine which of the sets are functions.
   a. f = {(2, 1), (4, 5), (6, 9), (5, 9)}
   b. g = {(3, 4), (5, 1), (6, 3), (3, 6)}
   c. h = {(2, 1)}
   d. t = {(7, 5), (8, 9), (8, 9)}


2. State the domain and range of the function g = {(4, 5), (8, 9), (7, 7),
   (6, 7)}.