You have two ways to view a two-variable data plot in the TI-Nspire Data & Statistics application: as an x-y scatter plot or as an x-y line plot. The x-y line plot is identical to the scatter plot except that adjacent points on a scatter plot are joined with a segment.
Press [MENU]→Plot Type→XY Line Plot to switch to an x-y line plot. Press [MENU]→Plot Type→Scatter Plot to revert to an x-y scatter plot. Alternatively, move your cursor to the plot and right-click ([CTRL][MENU]) to choose Connect Data Points or Hide Connecting Lines.
The data in an x-y scatter plot looks nearly linear (although an exponential function provides a better fit). To add a movable line to a graph, press [MENU]→Analyze→Add Movable Line.
Here are three ways to manipulate a movable line:
Perform a translation: Move the cursor to the center of the line until the crossed-arrow symbol appears. Press [CTRL][CLICK] to grab the line, and use the Touchpad keys to translate it. This changes the y-intercept of the line.
Perform a rotation: Move the cursor away from the center of the line until the
symbol appears. Press [CTRL][CLICK] to grab the line, and use the Touchpad keys to rotate it. This action changes the slope of the line.
Lock the y-intercept at 0: Press [MENU]→Analyze→Lock Intercept at Zero to lock the y-intercept at 0. If you choose to lock the y-intercept at 0, the movable line can only be rotated. Press [MENU]→Analyze→Unlock Movable Line Intercept to unlock the y-intercept.
Notice that the movable line is stored to the variable m1(x). This variable is available for analysis anywhere within the same problem.