Functions and Function Notation Quiz

Grade 8 · Math · Quiz

Evaluate functions, identify functions from tables and graphs, and interpret function notation.

Questions

1. If g(x) = x² + 2x - 1, what is g(3)?

   1. 12
   2. 14
   3. 10
   4. 16
   Show answer

   Answer: 14

   g(3) = 3² + 2(3) - 1 = 9 + 6 - 1 = 14.

2. Which table represents a function?

   1. x: 1,2,2,3 → y: 4,5,6,7
   2. x: 1,2,3,4 → y: 5,5,5,5
   3. x: 1,1,2,3 → y: 2,3,4,5
   4. x: 2,3,4,2 → y: 6,7,8,9
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   Answer: x: 1,2,3,4 → y: 5,5,5,5

   Each x-value is unique, so each input maps to exactly one output. The other tables repeat an x with different y-values.

3. What does f(0) represent?

   1. The slope of the function
   2. The output when x = 0
   3. The input when y = 0
   4. The domain of the function
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   Answer: The output when x = 0

   f(0) means substitute x = 0 into the function to find the corresponding output.

4. For f(x) = -2x + 6, find the value of x when f(x) = 0.

   1. x = 3
   2. x = -3
   3. x = 6
   4. x = -6
   Show answer

   Answer: x = 3

   Set -2x + 6 = 0: -2x = -6, x = 3.

5. A function is described by: {(1,3), (2,5), (3,7), (4,9)}. What is the range?

   1. {1, 2, 3, 4}
   2. {3, 5, 7, 9}
   3. {1, 3, 5, 9}
   4. {2, 4, 6, 8}
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   Answer: {3, 5, 7, 9}

   The range is the set of output (y) values: 3, 5, 7, and 9.

6. Which graph represents a function?

   1. A circle
   2. A vertical line
   3. A parabola opening upward
   4. An ellipse
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   Answer: A parabola opening upward

   A parabola passes the vertical line test. Circles, ellipses, and vertical lines do not.

7. If f(2) = 10 and f(2) = 6, then f is a valid function.

   Show answer

   Answer: False

   A function requires each input to map to exactly one output. x = 2 cannot produce both 10 and 6.

8. In function notation, f(x) is read as 'f _____ x'.

   Show answer

   Answer: of

   f(x) is read 'f of x,' indicating the output of function f at input x.

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