Generic Instructions for Using the TI-83 Graphing Calculator to Solve for the Equation of a Graph Line

1. Press the STAT key. Highlight EDIT, 1:Edit, then press ENTER. Input lists of data: use L1 for the "x" values; L2 for the "y" values. (Note: be careful--must have the same number of data entries for x and y!)
2. Press the 2nd, then Y= buttons. From the STAT PLOTS menu, choose 1:Plot1 and make the following settings:
   • Plot 1 (On)
   • Type: Scatter Plot
   • Xlist (L1)
   • Ylist (L2)
   • Mark (square)
3. Press the WINDOW key (manually set values), or press the ZOOM key and use the down-arrow key to highlight 9:ZoomStat and then press ENTER.
4. If necessary, press the GRAPH key.

   Solving for the Equation of a Graph Line

5. Press the STAT key. Use the right-arrow key to highlight CALC; use the down-arrow key to highlight 5:LinReg(ax+b) and press ENTER. Press ENTER again.
6. Press the Y= key. Press the VARS key; use the down-arrow key to highlight 5:Statistics..., then press ENTER.
7. Use the right-arrow key to highlight EQ, use the down-arrow key to highlight 7:RegEQ, then press ENTER.
8. Press the GRAPH key; from the scatter plot points, a graph line is drawn.
9. Press the TRACE key, then press the up-arrow key to select the Plot 1 tracing (you should see a "1" in the upper right-hand corner of the screen). Use the left- or right-arrow keys to trace the graph line; note the X and Y coordinates at the bottom of the screen.