# Lesson 2

Introduction to Functions

Let’s learn what a function is.

### Problem 1

Here are several function rules. Calculate the output for each rule when you use -6 as the input.

### Problem 2

A group of students is timed while sprinting 100 meters. Each student’s speed can be found by dividing 100 m by their time. Is each statement true or false? Explain your reasoning.

- Speed is a function of time.
- Time is a function of distance.
- Speed is a function of number of students racing.
- Time is a function of speed.

### Problem 3

Diego’s history teacher writes a test for the class with 26 questions. The test is worth 123 points and has two types of questions: multiple choice worth 3 points each, and essays worth 8 points each. How many essay questions are on the test? Explain or show your reasoning.

### Problem 4

These tables correspond to inputs and outputs. Which of these input and output tables could represent a function rule, and which ones could not? Explain or show your reasoning.

Table A:

input | output |
---|---|

-2 | 4 |

-1 | 1 |

0 | 0 |

1 | 1 |

2 | 4 |

Table B:

input | output |
---|---|

4 | -2 |

1 | -1 |

0 | 0 |

1 | 1 |

4 | 2 |

Table C:

input | output |
---|---|

1 | 0 |

2 | 0 |

3 | 0 |

Table D:

input | output |
---|---|

0 | 1 |

0 | 2 |

0 | 3 |