Name _________________
Date_________________
4.1 Day 3 Notes
Is it a function? Using the vertical line test and table to determine the answer:
The vertical line test is a visual way to determine if a graph is a function or not: You draw a
vertical line and if it only passes through a point once, it is a function.
1. A function? Yes
or
No
3. A function? Yes
or
No
2. A function? Yes
4. A function? Yes
or
or
No
No
Now you try:
5. A function? Yes
or
No
6. A function? Yes
or
No
7. A function? Yes
or
No
8. A function? Yes
or
No
You can also determine if a graph is a function by looking at the domain and range; a
function can only have one output (y) for each unique input (x):
1. A function? Yes
x
-2
-1
0
1
2
or
y
-3
-1
1
3
5
No
2. A function? Yes
x
-2
-1
0
1
2
or
y
2
1
0
-1
-2
No
3. A function? Yes
x
-2
-2
-3
-3
-1
or
No
4. A function? Yes
y
2
1
0
-1
-2
or
x
5
6
7
8
9
No
y
2
1
0
-1
2
Now you try:
5. A function? Yes
x
4
3
2
1
0
No
6. A function? Yes
y
3
2
1
0
3
7. A function? Yes
x
10
9
8
7
6
or
x
6
7
8
9
6
or
y
20
18
16
14
12
No
No
y
4
5
6
7
4
8. A function? Yes
x
2
3
4
5
6
or
y
9
9
9
9
9
or
No