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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
about functions, please do write back.

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

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