Using the Graphing Calculator(TI-83) for Linear Extrapolation/Forecasting by Jackie J___ and Sagal A____
1. Put data in lists L1& L2
2. Go to Window and put in appropriate max and min. values
3. Go to Plot, make sure all plots are off except the first one, and choose the type of graph you want.
5. To find equation of least squares: go to STAT,CALC, then 4:LinREG(ax+b), Press enter
6. If you want to make predictions you should put your equation in Y. Instead of doing step 5 do this: Linreg(ax+b) L1, L2, THEN GO TO THE VARS key :Y VARS:Function, and press Enter twice.
7. After doing this, when you graph your data your least squares line should appear.
8. To make predictions: Press Second key, trace, Value, and Enter in what value of x you want.