Download Function Tables and Graphs

Function Tables and Graphs
Function
• A function is when each input (x-value)
corresponds to exactly one output (y- value)
• In other words, when you substitute (x) into
an equation there is only one possible answer
(y)
Let me show you what I mean
• Let’s use the function y = 2x + 5
y = 2(0) + 5
if x = 0 y = 5
x
y
0
5
2
5
10
20
Fill in the function table for the
function y = 4x – 3
x
0
2
5
10
20
y
Fill in the function table for the
function y = 4x – 3
x
y
0
-3
2
5
5
17
10
37
20
77
Fill in the function table for the
function y = -3x + 5
x
0
2
5
-2
-5
y
Fill in the function table for the
function y = -3x + 5
x
y
0
5
2
-1
5
-10
-2
11
-5
20
Fill in the function table for the
1
function y = x - 4
2
x
0
2
5
-2
-5
y
Graphing a Function from a Function
Table
• When given a function you can graph it by
creating a function table and plotting the points
you generate.
• You can pick any points for x and substitute them
into the function for the output y
• You should plot at least 5 points to get a good
idea of what your graph looks like: 0, two positive
numbers, and two negative numbers.
Let’s Use the Functions We Worked
With Earlier
y = 2x + 5
x
0
2
5
-2
-5
y
Let’s Use the Functions We Worked
With Earlier
y = 2x + 5
x
y
0
5
2
9
5
15
-2
1
-5
-5
y = 4x – 3
x
0
2
5
-2
-5
y
y = 4x – 3
Two of our points go way off our graph.
It helps to show how steep the slope is.
x
y
0
-3
2
5
5
17
-2
-11
-5
-23
y = -3x + 5
x
0
2
5
-2
-5
y
y=
x
0
2
4
-2
-4
y
1
x
2
-4
Closure
• With a partner, graph the function y = -3x + 3
y = -3x + 3