[constant thinker]

Does anyone know if it's possible to have excel automatically graph a line if you were to give the equation for the line?

I spent an hour trying to get it to plot 2 linear lines. I couldn't even find anything in the help files.

I eventually gave up, and used my graphics calculator. Then looked in the table of values, inputed that into excel, and then finally graphed all the points.

[Yggdrasil]

In general for any continuous curve, you can put x values into one column (e.g. put "1" in A1 and  in A2 put "A1+1" then fill down until you get to the proper stopping point).  Then put in your formula into the next column (e.g. type "=2 * A1^2 + 3 * A1 + 5") and fill down.  When you make a chart of the data, choose scatterplot and there should be pictures of graphs on the choose chart type box.  Choose the picture with no dots and with either jagged or smoothed lines depending on your preference.

For a line, theoretically all you need is the starting and ending point and the above procedure will give you your line.

[Mr Peanut]

But, look at this free program:

http://www.mark-bishop.net/Dot%20NET/Plotter/Plotter%20Help.htm

[enahs]

It is quite trivial if you have a equation in the form Y=mX+b

Lets say we have the equation Y= 55.673x + 37.2

You already know one point on the line:
X:0, y:37.2

You know the slope, 55.673.
Using the definition of slope:
ΔY/ΔX

Or
Y₁-Y₂ = 55.673
X₁-X₂

You know the point (0, 37.2) is on the graph.
You can then pick the other point on the graph you want. Say you know you want the range of the X value to go up to 250.

So then you have:
φ- 37.2 = 55.673
250 - 0

Solve for φ, 13,955.45
Then just plot the 4 points

(0,37.2) and (250,13955.45)

You now have the graph of that equation, perfectly.

I agree it would be nice to have a function do that automatically if you can give it the equation (and more then just the linear equation Y=mX+b would be nice), but since it is very very easy, who cares.

[constant thinker]

Thanks for your replies.

As a side note, I love my TI-83. That thing is utterly amazing. I wish there was a PC version of a TI-83, with ALL the functionality.

[enahs]

As a side note, I love my TI-83. That thing is utterly amazing. I wish there was a PC version of a TI-83, with ALL the functionality.

There are programs that blow the TI-83 away for the computer.
However, there are programs like that.
http://www.ticalc.org/archives/files/fileinfo/84/8442.html

[constant thinker]

Thanks for the program enahs, especially since it's free. 

Now if only I could find my stupid link cable...