Graphing whole number functions

Introduction

A function is a rule that takes in and works on an input and gives an output. It is usually represented as fx = y, where x is the input variable and y is the output variable.

By giving different whole number values to x, values of y can be found from the function rule. The x and y values are put in a table and then plotted as a graph.

Plotting a graph

So, from a function rule, x and y values can found and put in a table and also plotted as a graph.

Conversely, from a graph we can find x and y values and make a table of those values and find the function rule for the given graph also.

Example 1

The table below describes a function. Graph this function.

Inputx	Outputy
0	0
2	4
4	8
6	12
8	16

Solution

Step 1:

From the table, we get the coordinates of the points as 0,0, 2,4, 4,8, 6,12, and 8,16

Step 2:

Making a plot of these points, we get

Example 2

The graph of a function is given below. Fill in the table for this function.

Solution

Step 1:

From the graph plot, we get the coordinates of the points as 0,0, 1,4, 2,9, 3,5, and 4,10

Step 2:

Making a table of the x and y values, we get

Inputx	Outputy
0	0
1	4
2	9
3	5
4	10