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# Algebra Functions

## Functions Are Functional

Jennifer Ledwith

A function is a set of data that has one distinct output for each input, but functions are much more than x and y living together on a Cartesian plane in a graph paper galaxy. They have applications in real life. Functions describe the relationship between an input and its output.

Graphs, charts, equations, and verbal descriptions – these depict functions.

Here are other words for input and output:

### Input:

• x-value
• independent variable
• independent quantity
• domain
• cause

### Output:

• y-value
• dependent variable
• dependent quantity
• range
• effect

As you have probably surmised, you control the input. Once the input travels through the function, you get your output. OK, I’m a big math nerd, but I will leave Algebra land to explain.

Imagine that you’re running late for math tutoring. You’re speeding 60 miles per hour in a 20 mile per hour school zone. A cop pulls you over and writes you a \$300 speeding ticket. Let’s break down this real world cause and effect situation.

Input: You chose to exceed the speed limit by 40 miles per hour.
Output: You received a speeding ticket.

You see, you can control how fast you’re going, but the consequence, or the output, is up to the cop.

### Algebra That’s Useful During March Madness

Let me give you another example. I have a perfect function that determines basketball scores. (Shhh…It’ll be our secret.)

y = 15x + 10
x is the number of hours per day that a basketball team practices.
y is the number of points scored in the game.

For a breakdown of the results in a table, refer to the Basketbal Scores Table.

For a depiction of the results in a graph, look at the Basketball Scores Graph in More Images.