Function notation: read and evaluate f(x), including f(x + 2) and f(2x)

Answer Key - Grade 9 Math Worksheet

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

1. 1.

   Ari's toy rocket climbs. Its height is f(s) = 6s − 4 meters after s seconds. What is f(7)?

   38
2. 2.

   Bo's robot builds a tower. The tower has f(m) = 4m + 12 blocks after m minutes. What is f(15)?

   72
3. 3.

   Esme's game gives stars. The score is f(r) = 7r − 9 after r rounds. What is f(6)?

   33
4. 4.

   Jun rides a school bus. The riders on board are f(s) = 3s + 7 after s stops. What is f(12)?

   43
5. 5.

   Luz invents a number game: f(x) = x² − 3x + 1. Luz tries the input −5. What is f(−5)?

   41
6. 6.

   Milo's calculator follows f(x) = x² + 2x + 5. Milo types in −4. What is f(−4)?

   13
7. 7.

   Noah sells cookies. The function c(n) gives the cost in dollars of n cookies, and c(5) = 12. What does c(5) = 12 tell us?

   • Each cookie costs $12
   • 12 cookies cost $5
   • 5 cookies cost $12
8. 8.

   Pia's plant is growing. The function h(w) gives its height in cm after w weeks, and h(6) = 30. What does h(6) = 30 tell us?

   • The plant grows 30 cm each week
   • After 30 weeks, the plant is 6 cm tall
   • After 6 weeks, the plant is 30 cm tall
9. 9.

   Zee's snack cart follows f(x) = 3x − 4 for the dollars earned after x sales. For which x does f(x) = 23?

   9
10. 10.

    Ari's sharpening game follows f(x) = 4x − 6 for the points after x pencils. For which x does f(x) = 42?

    12