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### Functions and Function Tables

```
Date: 05/11/99 at 17:14:53
From: chris
Subject: I don't understand functions and function tables

I asked my parents and various other people about functions but they
know absolutely nothing! I do not understand functions and function
tables. Can you help me?
```

```
Date: 05/20/99 at 13:48:47
From: Doctor Schwa
Subject: Re: I don't understand functions and function tables

One way to think of a function is as a rule. You give it some object,
and it replies with some other object. For example, a catalog for a
shirt company might have a function called price, and price of green
shirt = \$8 could be written as

price(green shirt) = 8

and we might also have

price(white shirt) = 6
and  price(yellow shirt) = 8
and price(tie-dye shirt) = 12

and so on.

In math, functions are usually rules that work with numbers. The
object you give is a number, and the reply is another number. For
instance, the function rule might be "add two," and if we name that
function f,

f(4) = 6
f(5) = 7
and so on.

In general we could write f(x) = x+2.

Now, if you want to make a function table, you take a rule, say
g(x) = x^2, and make a table like this:

x | g(x)
---+-----
-2 |  4
-1 |  1
0 |  0
1 |  1
2 |  4

and so on. You could continue the table as long as you want to.

I hope this helps clear things up for you! If you have more questions

- Doctor Schwa, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Functions

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