Student Goal

I can identify functions from tables, mappings, graphs, and rules.

Why It Matters

Functions are the language of Math 1. They help describe how one quantity depends on another.

Warm-Up

Warm-Up 1

If f(x) = 2x + 1, what is f(3)?

Warm-Up 2

True or false: One input can have two different outputs and still be a function.

Short Lesson

Standard Focus

NC.M1.F-IF.1 and NC.M1.F-IF.2: Function notation and interpretation

Student-Friendly Standard Goal

I can understand function notation and evaluate functions for inputs.

  • A function assigns each input exactly one output.
  • The same output can happen more than once, but one input cannot have two different outputs.
  • f(x) means the output of the function when the input is x.
  • Tables, graphs, equations, and situations can all represent functions.

Guided Examples

Guided Example 1

Evaluate a Function

Evaluate g(x) = -3x + 4 when x = -2.

Step 1

g(-2) = -3(-2) + 4

What is -3(-2)?

Guided Example 2

Check a Table

Decide whether the table represents a function.

Step 1

Inputs: -1, 0, 1, 2

Does any input repeat with a different output?

Practice

Problem 1

If h(x) = x^2 - 1, what is h(4)?

Problem 2

True or false: Inputs 1, 2, 3 with outputs 5, 5, 5 can be a function.

Problem 3

Which set is not a function?

Problem 4

If f(x)=5x, find f(6).

Problem 5

Choose the next step to evaluate p(-3)=2(-3)^2+1.

Reflection

How are you feeling about today's skill?

Optional reflection: What is one step, word, or representation from today that you want to remember when Math 1 starts?