Graphing y = mx+b

Date: 6/28/96 at 21:48:14
From: Anonymous
Subject: Graphing y = mx+b

Would you please explain to me the whole concept of graphing, algebra 
level. I don't understand what y=mx+b means and how to do slope 
intercept form. I am going into algebra 1 next year. Please help me.

Date: 6/30/96 at 15:49:44
From: Doctor Robert
Subject: Re: Graphing y = mx+b

An awful lot of algebra involves sets of ordered pairs.  I assume that 
you know how to graph ordered pairs on the x-y plane.  (The horizontal 
axis is the x-axis while the vertical axis is the y-axis.)  Consider 
the following ordered pairs  (0,1), (1,3), (2,5)(,3,7), (4,9), etc. 
You will notice that a rule which relates each of the numbers in the 
ordered pairs is

  y = 2x + 1

The rule says, take the value of x, multiply it by 2 and add 1 and you 
have the value of y!  If you draw the straight line that contains all 
of the ordered pairs above, you will notice that the line has a slope 
of 2 and that it crosses the y-axis at 1.  So, if you are given an 
equation in the form y = mx + b, you know that the slope of the line 
is m and that the line crosses the y-axis at the number b.  I hope 
that this helps.

-Doctor Robert,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/