If a graph looks blank or flat, the window is wrong - not the function. Choosing the window well is half of most graphing questions.
In short: A viewing window is the range of x and y values the graph screen displays. Setting it well means choosing minimum and maximum values that show every feature the question asks about, such as intercepts and turning points. A poor window can hide a root or turning point entirely, so adjust it before reading any values.
| TI-84 Plus CE | Casio fx-CG50 and fx-CG100 | TI-Nspire CX | |
|---|---|---|---|
| Key sequence | Press WINDOW to set Xmin/Xmax/Ymin/Ymax; ZOOM → 0:ZoomFit auto-fits y to the x-range; ZOOM → 6:ZStandard resets to −10…10. | Press SHIFT → F3 (V-Window) to set the range, or Zoom (F2) → Auto. | menu → Window/Zoom → Window Settings, or Zoom-Fit / Zoom-Standard. |
Tip: For a real-world model, set Xmin/Xmax to the domain in the question and let the y-range auto-fit.
Tip: For a real-world model, set Xmin/Xmax to the domain in the question and let the y-range auto-fit.
Tip: For a real-world model, set Xmin/Xmax to the domain in the question and let the y-range auto-fit.
Here's a real IB-style question that uses exactly this technique.
A population is modelled by P(t) = 200(1.15)ᵗ for 0 ≤ t ≤ 20. Suggest a suitable window to show the full graph, and state P(20) to the nearest whole number.
If a graph looks blank or flat, the window is wrong - not the function. Choosing the window well is half of most graphing questions. The graph looks blank when you first draw it - almost always a window problem, not a wrong function. A real-world model has a natural domain (e.g. 0 ≤ t ≤ 20), so the default window won't show it properly.
1. Decide the x-range from the question (e.g. 0 ≤ t ≤ 10) and a sensible y-range. 2. Press WINDOW to set Xmin/Xmax/Ymin/Ymax; ZOOM → 0:ZoomFit auto-fits y to the x-range; ZOOM → 6:ZStandard resets to −10…10. 3. Re-graph after changing the window.
1. Decide the x-range from the question (e.g. 0 ≤ t ≤ 10) and a sensible y-range. 2. Press SHIFT → F3 (V-Window) to set the range, or Zoom (F2) → Auto. 3. Re-graph after changing the window.
1. Decide the x-range from the question (e.g. 0 ≤ t ≤ 10) and a sensible y-range. 2. menu → Window/Zoom → Window Settings, or Zoom-Fit / Zoom-Standard. 3. Re-graph after changing the window.
For a real-world model, set Xmin/Xmax to the domain in the question and let the y-range auto-fit.
In the worked example on this page (2 marks, Paper 2), the marks are: M1: x-range covers the given domain; y-range covers P(20); A1: P(20) ≈ 3269.
Questions that need this technique link back to this guide. Try one in practice mode, or see every GDC guide.