What is a function? | Functions and their graphs | Algebra II

Alphabets Sounds Video

share us on:

In this lesson, we explored the concept of functions in mathematics, likening them to machines that transform inputs into outputs based on specific rules. We examined examples of functions, such as determining outputs for even and odd inputs, and learned how to identify non-functions by recognizing instances where a single input yields multiple outputs. Understanding these principles equips us with essential skills for tackling more advanced mathematical concepts.

Understanding Functions: A Fun Guide

Hey there! Today, we’re diving into the world of functions in math. Functions might sound a bit tricky, but think of them as cool machines that take something in, do some magic, and give you something out. Let’s explore what functions are, see some examples, and learn how to tell if something is a function or not.

What is a Function?

Imagine a function as a machine. You put something in, it works on it, and then gives you a result. The thing you put in is called an input, usually shown as x. The function itself often gets a name like f.

Example of a Function

Let’s look at a function that works like this:

  • If x is even, the function gives you x squared: f(x) = x2
  • If x is odd, the function adds 5 to x: f(x) = x + 5

Let’s try it out:

  • Inputting 2: Since 2 is even, we do f(2) = 22 = 4.
  • Inputting 3: Since 3 is odd, we do f(3) = 3 + 5 = 8.

See how the function changes what it does based on whether the number is even or odd? That’s the magic of functions!

Generalizing Function Notation

Functions can be super creative. For example, let’s define a function h(a) that finds the next biggest number starting with the same letter as the input:

  • For h(2): The number 2 starts with ‘T’, so the next biggest number starting with ‘T’ is 3.
  • For h(8): The number 8 starts with ‘E’, so the next biggest number starting with ‘E’ is 11.

Functions can be as creative as you want them to be!

Traditional Function Examples

You might already know some simple functions like:

  • y = x + 1

In function notation, this is f(x) = x + 1. Let’s see what happens with different inputs:

  • f(0) = 0 + 1 = 1
  • f(2) = 2 + 1 = 3

For every input x, you get an output that’s one more than x. Easy, right?

What is Not a Function?

For something to be a function, each input must have only one output. Let’s look at a circle’s equation:

  • x2 + y2 = 4

If you try x = 1, you get two possible y values: y = √3 and y = -√3. Since one input gives two outputs, this isn’t a function.

Conclusion

Functions are like magical math tools that help us understand how inputs and outputs relate. Knowing what makes something a function, seeing examples, and spotting non-functions are key skills in math. With this knowledge, you’ll be ready to tackle more complex math challenges!

  1. How did the analogy of a function as a “machine” help you understand the concept of functions better?
  2. Can you think of a real-life example where a function-like process is used? How does it compare to the mathematical definition of a function?
  3. Reflect on the examples provided in the article. Which example did you find most helpful in understanding how functions work, and why?
  4. What new insights did you gain about functions from the section on generalizing function notation?
  5. How does the explanation of what is not a function help clarify the definition of a function for you?
  6. In what ways do you think understanding functions can be beneficial in solving real-world problems?
  7. What challenges do you anticipate when trying to determine if a relation is a function or not, based on the article?
  8. How might you explain the concept of functions to someone who is new to the topic, using your own words and examples?
  1. Function Machine Activity

    Imagine you are a function machine! Create a list of inputs (numbers) and decide what your function will do to each input. For example, if your rule is to add 3 to even numbers and subtract 2 from odd numbers, apply this to your list and share your results with the class.

  2. Function Storytelling

    Write a short story where a character encounters different functions in their daily life. Describe how each function changes the input they provide and what the output is. Be creative and think of fun scenarios where functions might appear!

  3. Function Art

    Create a visual representation of a function using art supplies. Use colors and shapes to show how different inputs are transformed into outputs. Present your artwork to the class and explain the function you chose to represent.

  4. Function Detective

    Become a function detective! Find examples of functions in real life, such as vending machines or calculators. Explain how these examples take an input, perform a function, and produce an output. Share your findings with the class.

  5. Function Game

    Design a simple game where players must guess the rule of a function based on given inputs and outputs. Provide a series of inputs and their corresponding outputs, and challenge your classmates to identify the function rule. The first to guess correctly wins!

FunctionsA relationship or expression involving one or more variables, where each input has a single output. – In mathematics, functions are used to describe how one quantity changes with respect to another.

InputThe value or values that are put into a function to get an output. – When you input the number 3 into the function f(x) = x + 2, the output is 5.

OutputThe result obtained after applying a function to an input. – The output of the function f(x) = 2x when the input is 4 is 8.

EvenAn integer that is divisible by 2 without a remainder. – The number 8 is even because it can be divided by 2 to give 4.

OddAn integer that is not divisible by 2, leaving a remainder of 1. – The number 7 is odd because dividing it by 2 leaves a remainder of 1.

NotationA system of symbols used to represent numbers, functions, and operations in mathematics. – In algebra, the notation f(x) is used to denote a function named f with x as the variable.

ExampleA specific case or instance used to illustrate a concept or method. – An example of solving a linear equation is finding x in the equation 2x + 3 = 7.

EquationA mathematical statement that asserts the equality of two expressions. – The equation 3x + 5 = 11 can be solved to find the value of x.

ValuesThe numerical quantities assigned to variables or constants in an equation or expression. – In the equation y = 2x + 1, the values of x determine the corresponding values of y.

ToolsInstruments or techniques used to solve mathematical problems or perform calculations. – Graphing calculators are useful tools for visualizing functions and their graphs.

All Video Lessons

Login your account

Please login your account to get started.

Don't have an account?

Register your account

Please sign up your account to get started.

Already have an account?