Write an exponential function from a table, graph or story

Answer Key - Grade 9 Math Worksheet

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

1. Read this first

   Growth table

   x	y
   0	3
   1	12
   2	48
   3	192

2. 1.

   Pia tracks a seed swap where each round brings in 4 times as many seeds. What function fits the table? Start with y =.

   y = 3(4)^x
3. 2.

   Tala's art club tracks crayon drawings in a pattern game. What function fits the table? Start with y =.

   y = 4(5)^x
4. 3.

   Zee stacks paper cups in a pattern game. What function fits the table? Start with y =.

   y = 6(2)^x
5. 4.

   Bo's kite-club graph shows a pattern. What function fits the graph? Start with y =.

   y = 9(2)^x
6. 5.

   Esme's graph shows a shrinking pattern. What function fits the graph? Start with y =.

   y = 48(1/2)^x

7. Growth table

   x	y
   1	24
   2	72
   3	216
   4	648

8. 6.

   Noah's train-game table starts at x = 1. What function fits the table? Start with y =.

   y = 8(3)^x
9. 7.

   A video-game coin is worth 4 points at level 0, and its value triples each level. Pia wants its value at level x. What function gives it? Start with y =.

   y = 4(3)^x
10. 8.

    A science video starts with 50 bacteria, and the count doubles every 20 minutes. x is the number of 20-minute periods. What function gives Ren the count? Start with y =.

    y = 50(2)^x
11. 9.

    Tala's block pattern has 5 blocks at stage 0, and each stage has 4 times as many blocks. What function gives the blocks at stage x? Start with y =.

    y = 5(4)^x
12. 10.

    Zee folds a stack of 6 sheets in half again and again. Each fold doubles the layers. What function gives the layers after x folds? Start with y =.

    y = 6(2)^x