How to simplify the equations in ti 84 ??

There is no such thing as a TI89 Plus Silver Edition.

If you mean the TI-89 or TI-89 Titanium, press diamond / (the diamond key below the 2ND key, then the divide key).

If you mean the TI-83 Plus Silver Edition or the TI-84 Plus Silver Edition, press MATH left-arrow 4 .

Your data must be in two lists L1 (for x-values), and L2 (for y-values). This is the default setting. Open the STAT utility, go to the regression models. Select your model then press ENTER. The command echoes on the main screen. For example let the regression be something called LinReg.
On the main screen you see LinReg
Complete the command line as follows
LinReg L1, L2, Y1, ENTER
You see the statistics including the regression equation.
If you go to Y= Editor you will see that Y1 contains the regression equation.
If you have already drawn the scatter plot for your data, pressing GRAPH will superpose the scatter plot and the regression curve., and you will be able to judge the goodness of the fit.

It denotes an exponent of ten. For example, 1.1E4 means 1.1 times 10 to the 4 or 11000 (eleven thousand).

You're probably trying to graph a function that does not involve stat plot features. You can correct this by turning off the stat plot features. Press "2ND" "STAT PLOT" and then select 4:PlotsOff.

There isn't one. If you want to convert a value from decimal to fraction, use the >Frac function (press MATH 1). If you want to enter a fraction, simply enter the numerator, divide, then the denominator.

For example, to calculate 1/4 + 1/3, press
( 1 / 4 ) + ( 1 / 3 ) MATH 1 ENTER
and you'll see 7/12.

Press 4 then press math. Select #5. You'll be back at the home screen now type 90 and press enter. You can use this for any root.

Ask here for the TI-84 manual, they will get it for you.

I do not think that you can DELETE it, you probably just cleared the equation, just put another equation into Y=, and it will work.

otherwise, if you don't have any programs you need or so... just press 2nd +

Scroll down to reset, and press clear RAM

The TI 83, 84 seris can not store more than 10 equations. the TI 86 and above can have infinate, but not the 83, 84s. If you have catalog help in your apps, you can run that, and it will be able to tell you all the syntax of every function it has.

Enter the fraction for example: enter 8/12.
The answer will be .666666
Then click Math (which is located under the Alpha button).
Click the ->Frac button (the first one).
It should come up as Ans->Frac.
Click Enter.
It should now read 2/3 which is 8/12 reduced.
Note: I have a TI-84 Plus Silver Edition, and the TI-84 Plus might not have this function, but that is how I do it on my TI-84 Plus Silver Edition