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Graphing Linear Equations

```Date: 04/11/2003 at 17:40:47
From: Aimee
Subject: Graphing linear equations and Inequalities

I was recently on math.com and I am a little confused. They asked me
to find the slope and the y-intercept. But how do I find the points on
the line so that I can get the answers? There aren't any dots on the
lines to find the coordinates.

```

```
Date: 04/14/2003 at 00:15:07
From: Doctor Ian
Subject: Re: Graphing linear equations and Inequalities

Hi Aimee,

You can choose _any_ points on the line to find the slope and
intercept.

For example, pick any value of x, and mark it on the x-axis.

+---|---*---|---|---|
1   2   3   4   5

Then move straight up (or down) until you hit the line.

|          /
6 -         /
|        /
5 -       .
|      /.
4 -     / .
|    /  .
3 -   /   .
|  /    .
2 - /     .
|/      .
1 /       .
|       .
+---|---*---|---|---|
1   2   3   4   5

Then move straight over until you hit the y-axis.

|          /
6 -         /
|        /
5 *........
|      /.
4 -     / .
|    /  .
3 -   /   .
|  /    .
2 - /     .
|/      .
1 /       .
|       .
+---|---*---|---|---|
1   2   3   4   5

Those x and y values are the coordinates of one point on the line.  In
this case,

x=2, y=5  -->  (2,5)

is one point on the line.  Do the same thing again to find a second
point,

|          /
6 -         /
|        /
5 *........
|      /.
4 -     / .
|    /  .
3 *....   .
|  /.   .
2 - / .   .
|/  .   .
1 /   .   .
|   .   .
+---*---*---|---|---|
1   2   3   4   5

and you can use those two points to find the slope. Note that you may
need to do a little exploring to find x values that give you nice,
round y values. That isn't strictly necessary, but it can make your
calculations easier.

Does this help?

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Equations, Graphs, Translations
High School Linear Equations

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