Is it a function? Vertical line test, and reading values from graphs and tables

Answer Key - Grade 9 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Jun plots dots from a bus-stop survey (one dot is a very sleepy stop). The vertical line at x = 3 touches the dots (3, 2) and (3, 6). Is it a function?

   • Yes: every input has an output
   • No: inputs 1 and 3 share the output 2
   • No: the input 3 has two outputs, 2 and 6
2. 2.

   Luz plots game levels and star counts as dots. The vertical line at x = 2 touches the dots (2, 1) and (2, 4). Is it a function?

   • No: the dots do not make a straight line
   • Yes: every input has an output
   • No: the input 2 has two outputs, 1 and 4
3. 3.

   Milo plots kite heights over time as dots. No vertical line touches two dots. Is it a function?

   • No: the dots do not make a straight line
   • Yes: no vertical line touches two dots
   • No: inputs 3 and 5 share the output 1
4. 4.

   Noah's sunflower grows. The graph shows f(w), its height in cm after w weeks. What is f(2)?

   5
5. 5.

   Pia's toy rocket climbs. The graph shows f(s), its height in meters after s seconds. What is f(3)?

   10
6. 6.

   Ren fills a pool. The graph shows f(m), the liters in it after m minutes. What is f(1)?

   7
7. 7.

   Tala bikes a hilly road. The graph shows f(h), the km ridden after h hours. What is f(4)?

   8

8. Read this first

   Use the table

   input x	output f(x)
   3	19
   4	25
   5	box
   6	37

9. 8.

   Ari fills a table for the robot rule f(x) = 6x + 1. What number goes in the box for input 5?

   31
10. 9.

    Bo fills a table for the lamp rule f(x) = 3x + 5. What number goes in the box for input 7?

    26
11. 10.

    Esme fills a table for the gift rule f(x) = 5x + 2. What number goes in the box for input 4?

    22