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Is It a Function? (Vertical Line Test) — Easy Worksheet 2
Grade 8 · Whoobee Name: ____________________ Date: __________
Does each graph show y as a function of x? Write Yes or No.
How to solve
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Example
Does the graph show y as a function of x? Write Yes or No.
Answer: No
Not quite. The answer is
💡 Each point has a different x-value (−4, −3, 1, 4), so no vertical line passes through two points. It is a function: Yes.
✓ Correct!
Not quite. The answer is
💡 Each point has a different x-value (−4, −3, 1, 4), so no vertical line passes through two points. It is a function: Yes.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 The points (−5, −1) and (−5, −5) lie on the same vertical line x = −5, so the input −5 has two outputs. It is not a function: No.
✓ Correct!
Not quite. The answer is
💡 The points (−5, −1) and (−5, −5) lie on the same vertical line x = −5, so the input −5 has two outputs. It is not a function: No.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 The points (−5, −3) and (−5, −2) lie on the same vertical line x = −5, so the input −5 has two outputs. It is not a function: No.
✓ Correct!
Not quite. The answer is
💡 The points (−5, −3) and (−5, −2) lie on the same vertical line x = −5, so the input −5 has two outputs. It is not a function: No.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Each point has a different x-value (−4, −3, −2, 0), so no vertical line passes through two points. It is a function: Yes.
✓ Correct!
Not quite. The answer is
💡 Each point has a different x-value (−4, −3, −2, 0), so no vertical line passes through two points. It is a function: Yes.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 The points (5, −1) and (5, −4) lie on the same vertical line x = 5, so the input 5 has two outputs. It is not a function: No.
✓ Correct!
Not quite. The answer is
💡 The points (5, −1) and (5, −4) lie on the same vertical line x = 5, so the input 5 has two outputs. It is not a function: No.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 The points (−4, 1) and (−4, 4) lie on the same vertical line x = −4, so the input −4 has two outputs. It is not a function: No.
✓ Correct!
Not quite. The answer is
💡 The points (−4, 1) and (−4, 4) lie on the same vertical line x = −4, so the input −4 has two outputs. It is not a function: No.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Each point has a different x-value (−4, −2, 1, 3), so no vertical line passes through two points. It is a function: Yes.
✓ Correct!
Not quite. The answer is
💡 Each point has a different x-value (−4, −2, 1, 3), so no vertical line passes through two points. It is a function: Yes.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Each point has a different x-value (−3, −2, 0, 1), so no vertical line passes through two points. It is a function: Yes.
✓ Correct!
Not quite. The answer is
💡 Each point has a different x-value (−3, −2, 0, 1), so no vertical line passes through two points. It is a function: Yes.
💡 How to solve: Is It a Function? (Vertical Line Test)
Imagine sliding a vertical line across the graph. If a vertical line ever touches the graph in more than one place, one input has two outputs and the graph is not a function. If every vertical line touches it at most once, it is a function. A slanted or horizontal line passes the test; a vertical line fails it.
Try a similar one
Does the graph show y as a function of x? Write Yes or No.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
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Is It a Function? (Vertical Line Test) — Easy Worksheet 2
Does each graph show y as a function of x? Write Yes or No.