Evaluate and graph an exponential function

Answer Key - Grade 9 Math Worksheet - Challenge Me

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

1. 1.

   Tala's math-club puzzle uses f(x) = 5 · (1/2)^x. What is f(-3)?

   40
2. 2.

   Zee's jar puzzle uses f(x) = 7 · (1/2)^x. What is f(-2)?

   28
3. 3.

   Ari's cup puzzle uses f(x) = 4 · (1/3)^x. What is f(-2)?

   36
4. 4.

   Bo's box puzzle uses f(x) = 2 · (1/4)^x. What is f(-2)?

   32
5. 5.

   Kira's train-ticket game uses f(x) = 7 · 2^x points. For which input x is f(x) = 224?

   5
6. 6.

   Luz's library game uses f(x) = 2 · 10^x points. For which input x is f(x) = 2000?

   3
7. 7.

   Milo plots data that shrinks by the same factor each step. Which function matches the graph?

   • y = 80 − 40x
   • y = 80 · 2^x
   • y = 40 · (1/2)^x
   • y = 80 · (1/2)^x
8. 8.

   Noah plots data that shrinks by the same factor each step. Which function matches the graph?

   • y = 18 · (1/3)^x
   • y = 54 · 3^x
   • y = 54 · (1/3)^x
   • y = 54 − 36x
9. 9.

   Pia plots data that shrinks by the same factor each step. Which function matches the graph?

   • y = 128 · 4^x
   • y = 128 − 96x
   • y = 32 · (1/4)^x
   • y = 128 · (1/4)^x
10. 10.

    Ren plots data that shrinks by the same factor each step. Which function matches the graph?

    • y = 243 − 162x
    • y = 81 · (1/3)^x
    • y = 243 · (1/3)^x
    • y = 243 · 3^x