Associated Topics || Dr. Math Home || Search Dr. Math

### Graphing an Equation

```
Date: 4/4/96 at 22:10:44
From: Anonymous
Subject: Graphing

How do you graph 2x-y = 10? I just don't understand how to do it.
```

```
Date: 9/1/96 at 18:29:31
From: Doctor Jim
Subject: Re: Graphing

Since neither x or y has an exponent you can see, they are both called
linear, so this equation forms a line.

The easiest way to graph this is to pick some points (x,y) that make
the equation true, like x=6, y=2, because 2*6-2 = 12-2=10.
If x=7 then y=4.  In fact there are an infinite number of solutions
for this equation.  No matter what you pick for x, you can find a
y that will make the left side be 10.

Another way to graph it would be to solve it for y.
Subtract 2x from both sides so -y=-2x+10, then divide both sides
by -1, so that y = 2x - 10.

In this form the number in front of x is the slope. In this case the
line goes up 2 for every 1 it goes to the right, and the y-axis
intercept is -10, so it crosses the y-axis at (0,-10).  Remember that
the slope means the y coordinate increases 2 every time the x
coordinate increases 1.  So more points on the line could be found by
adding 1 to the x and 2 to the y, i.e., (1,-8), (2,-6), (3,-4), etc.

-Doctor Jim,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
High School Basic Algebra

Search the Dr. Math Library:

 Find items containing (put spaces between keywords):   Click only once for faster results: [ Choose "whole words" when searching for a word like age.] all keywords, in any order at least one, that exact phrase parts of words whole words

Submit your own question to Dr. Math
Math Forum Home || Math Library || Quick Reference || Math Forum Search