Mystery Machine
Test the machines.
Pick an input.
Follow the machine's rule to find the output.
Make a Prediction
You will investigate several mystery machines. Some are functions & some are not. What do you THINK makes a machine a function?
Machine A
Rule: Multiply by 2
INPUT → × 2 → OUTPUT
Test Machine A
You put 5 into Machine A. What comes out?
Machine B
Rule: Add 3
INPUT → + 3 → OUTPUT
Test Machine B
You put 4 into Machine B. What comes out?
Something Interesting......
Machine C gave these results:
1 → 5
2 → 5
3 → 8
4 → 10
Look carefully at the inputs & outputs.
Don't decide anything yet. Just notice.
What do you notice?
Look at Machine C. Which statement is true?
Machine D
Machine D gave these results:
1 → 4
2 → 6
3 → 8
2 → 10
Look carefully. Something different happened this time.
What happened in Machine D?
Which statement best describes what happened?
Make Your Call
One of these machines follows the special function rule. Which one do you THINK is a function?
选择所有适用项
- A
- B
You Discovered the Rule!
Machine C IS a function.
Different inputs CAN have the same output.
Machine D is NOT a function.
One input (2) had two different outputs.
A FUNCTION:
Every input has exactly ONE output.
INPUT → ONE OUTPUT
Function or Not?
Look at this relationship: 1 → 7 2 → 9 3 → 7 4 → 12 Is this a function?
Prove it!
Why is the relationship you just looked at a function?