Can't get the calc to graph two equations at the same time after they have been entered into y=

Error 07 Syntax
Means you made a typing error while entering the equation. Using the minus sign instead of the negation sign (change sign) (-), can produce a syntax error. Maybe you need to explicitly type the multiplication sign
y= (-) 1.5*x +3
Try entering it as 3 - 1.5*x

After you enter the data draw the SCATTER plot first.
When you perform the (linear) regression analysis LineReg, save the regression equation to a function, for example Y1
The syntax is
LineReg L1, L2, Y1 ENTER


From the Stat>CALC menu press LineReg
The command echoes on command line
Press [2nd][1] to enter the L1 list on command line
Press [,] to separate
Press [2nd] [2] to enter L2 on the command line
Press [,] the comma again
Press [VARS][>][Y-Vars][1~Function][1:Y1] [ENTER]
Press [GRAPH] to have the regression line equation drawn
on the same screen as the Scatter Plot you drew before.

I do not know what you mean by regulate, but if you want to perform a regression analysis using data from L1 and L3, all you have to do is to specify the lists to be used.
For example if you have to perform QuadReg on L1,L3,

1. Press [STAT] button,
   
2. then Right Arrow to select CALC(ulate)
   
3. then [5:QuadReg]
4. The command QuadReg echoes on main screen as QuadReg .
   
5. At this point press [SHIFT][1] to select (L1), then [COMMA], then [SHIFT][3] to select (L3) , and finally [ENTER].
6. The result will be displayed after regression is performed.
7. If you want to save the regression equation in Y1 so as to graph it over the scatter plot you enter QuadReg L1, L3, Y1 [ENTER]
   

The regression equation can be copied automatically in a Yx variable. You need not enter it manually(?).
Example: Suppose you are performing a quadratic regression on data stored in L1 and L2.

1. From the [Stat][

To clean the slate so to speak, just reset the RAM.

1. Press [2nd][+] to access the (MEM)ory management function
2. Press [7:Reset]
3. Press [1:All Ram]
4. Press [2:Reset]
5. Press [CLEAR] to erase the "RAM cleared" Message

Calc

I assume you know how to enter data in your calculator. The keystrokes in the following pertain to TI92/92Plus/ Voyage 200 PLT. The main differences with the TI89/Ti89 Titanium is that the function keys F6,F7,F8 are not accessed directly but by the key sequences [2nd][F1], [2nd][F2], and [2nd][F3] respectively

1. CLEAN THE SLATE (so to speak) and ENTER DATA

In Home folder run F6: NewProb to reset the configuration.
Press Apps, and select 6: data/Matrix editor. Select a new data set


Give it a name: here testing.



Press OK/ENTER, The data entry screen opens, enter your values.


When you finish press F2.PlotSetUp.

2. Statistical plot setup and scatter plot drawing

.

Press F1:define to configure Plot1. Choose Scatter, then choose a mark for the data point. I select 5:Dot. and press [ENTER


Select the data column X=c1, Y=c2



Press ENTER to save configuration. Press [CTRL] [GRAPH] On my TI92 the CTRL key is the [Diamond] key. On the following graph I changed the mark to a cross to see the data point better. I also played with the window dimension. You can also do that with ZoomStat. The graph remind me of a parabola (I know I chose the exact values)



3. STATISTICAL CALC. AND REGRESSION ANALYSES.

Now we have to find the equation that fits these data best.
You press APPS 6:Data/ Matrix editor but you select current to return to your data set. You are taken to the data entry editor (Figure 3 above). In that screen Press F5:Calc to edit the type of statistics you want

On first line select the type of regression model : Linear Regression, QuadReg quadratic regression (or anything else available) X is from column1, Y is from column 2. Store RegEQ The regression equation in say Y1(x)



Press ENTER to save to get the Regression Equation. Here it is
As you can see I cheated: a perfect parabola. R^2 =1.



And here the best fit represented on same graph as the statistical data



Usually you have to try different regression models, until you find the one that fits best the experimental data.

The calculator only displays from -10 to 10 on the x and y axes, and both of your lines are outside of that range. However, it is easy to change that.

1. Hit the gray "WINDOW" button that is directly under the screen
2. Change "Xmax" to 150
3. Change "Ymax" to 200

Remember to change both of those values back to 10 when you are done with this problem!

Here's how to graph it:
1. Hit the "Y=" button
2. Enter your first equation after Y1, and your second equation after Y2
3. Look over both the equations to make sure you typed them correctly
4. Hit the "GRAPH" button
5. If you don't see the intersection you will need to adjust Xmax and Ymax again
6. Hit Hit "2ND" and the "TRACE" to bring up the "CALC" menu
7. Scroll down to "intersect" and hit enter
8. Hit enter 3 times (You use the first and second curve options when you have more than 2 lines)
9. It should display the coordinates at the bottom
10. I got (76, 142.1) for the intersection

Thanks for asking this question! I used to do this a much harder way, but while I was calculating the answer to your question I hit a wrong button and accidentally found this method!

This is simple... Back up all RAM, (press second+, then 2, then 1, press enter to back up something if backed up it will have a star by it) Then clear your RAM (pull out your batteries while the calc is still on or press second+, then 7, then 1)
Hope this helps!

You are probably entering the equation wrong. Dont do this: 3600=x(2+2) You have to enter the equation 3600=x*(2+2)

Srry my friend the ti 83 is no magnificent Ti-89. meaning: you have to solve it yourself. There is a method for graphing though. Set the equation equal to zero and then plug the stuff on the other side of the equation into a graph by pressing y= and then typing it in. Then hit graph. Wait for the graph and then hit 2nd calc and select zeros. Bring your cursor using hte arrow keys close to where the line hits the x axis and press enter and then do the same except to the right of that point and then press enter twice and it will display the y which should be the answer
There are quadratic formulas for calculators programmed in tibasic for the calc but other than that there is no way to solve it