TI-Nspire CX II field manual for IB Math
Reading a graph: trace and zoom
Move a cursor along a plotted curve to read coordinates from it, and use the zoom menu to choose the viewing window deliberately.
Trace the graph of y=x−32x+1 to read coordinates from it, and use the zoom menu to locate its vertical asymptote.
Trace walks the cursor along the curve. With a graph on screen, press → Trace → Graph Trace. A cursor appears on the curve with its coordinates beside it, and the left and right arrows move it along. If several functions are plotted, the up and down arrows move between them.
It stops at anything interesting. Unlike a plain pixel walk, the Nspire's trace pauses and labels zeros, maxima, minima and intersections as the cursor passes them, printing a small word such as zero next to the point. This is often the quickest way to find a feature you were not specifically looking for. Press to leave trace.
Typing a number jumps straight there. While tracing, type a value and press : the cursor goes to that x rather than walking to it.
The zoom menu. → Window / Zoom. Zoom Box lets you click two opposite corners and snaps the window to that rectangle. Zoom Standard is the way back when the window has become unusable. Zoom Fit keeps the x-range and rescales y to the values the function actually takes. Window Settings lets you type the four bounds directly, which is the right choice when a question names the domain.
The standard window is not square. The Nspire's default view is wider than it is tall, roughly three units across for every two up, so a circle drawn on it looks like an ellipse and a slope looks shallower than it is. Zoom Quadrant 1 and Zoom Square fix the aspect ratio when the shape matters.
Tip: use trace to pin down a vertical asymptote. There is no asymptote finder on any calculator, but trace will bracket one. Graph y=x−32x+1 and trace rightwards towards x=3. The y-readout climbs steeply negative, then flips to a large positive value in a single step. The asymptote lies between the last two x-values you saw.
Narrow the window by hand, not with a box. Near the asymptote the curve plunges far outside any small y-range, so a zoom box drawn there would contain no curve at all. Open → Window / Zoom → Window Settings, type the bracket into x, and open y wide, for example −1000 to 1000, so both branches stay on screen. Trace again, and the jump between the two branches narrows the bracket by the same factor as the window.
The vertical asymptote is at x=3.00 to 3 s.f. To read any value from a graph more precisely, shrink the window and trace again.