How do you learn the TI-Nspire CX II and CX II CAS?

What are documents, problems and pages?

A document is the file your work is saved in. It contains problems, and each problem contains pages. A page starts with one application, and you can split it into as many as four work areas. The tab at the top left shows where you are: 1.2 means problem 1, page 2.

• Add a page with an application: ctrl doc lists nine applications, from 1 Add Calculator to 9 Add Python.
• Insert a problem or an empty page: doc › 4 Insert › 1 Problem or 2 Page.
• Turn the page: ctrl ◄ and ctrl ►.
• See every page: ctrl ▲ opens the Page Sorter, a thumbnail view grouped by problem.

When should I use the Scratchpad instead of a document?

Press home. The left side is the Scratchpad with A Calculate and B Graph, the right side lists your documents. Use the Scratchpad for a quick number in the middle of homework: type 7+8, press enter, done. pad switches between its Calculate and Graph halves.

The Scratchpad has no file behind it, so anything you need tomorrow belongs in a document. It also lacks the Functions & Programs menu, which means user-defined functions and programs need a real document page. To return to the document you had open, press home and choose 4 Current.

Which keys should I learn first?

• The touchpad. Slide to move the pointer, press an edge to step one field or line, and press the middle, click, to select.
• esc closes a menu, palette or dialog without doing anything. If you are lost, press it twice.
• menu opens the commands of the application you are in. ctrl menu opens the context menu of whatever the cursor is on.
• ctrl is the second-function key: ctrl enter gives a decimal answer, ctrl (−) pastes the last answer, ctrl ÷ writes a fraction template.
• Two minus keys. (−) is the sign of a negative number, − subtracts. Mixing them up usually ends in an error message.

The bottom of the keypad is a full keyboard with one key per letter, so typing x or a needs no shift key.

Why does the calculator answer 125/4 instead of 31.25?

The Calculator page answers exactly unless you ask for a decimal. 250/8 returns 125/4, and on a CAS model √8 returns 2·√2. Press ctrl enter instead of enter and the same input comes back as 31.25 or 2.82843.

Without CAS, fractions still stay exact, but square roots and π come back as decimals. How a document calculates is set in doc › 7 Settings & Status › 2 Document Settings…, and the settings travel with the file.

How do I graph a function and find a zero?

1. Add a Graphs page with ctrl doc. The entry line f1(x)= is already waiting.
2. Type the function and press enter. The curve is drawn and labeled.
3. For a second function, press menu › 3 Graph Entry/Edit › 1 Function, or ctrl G.
4. Press menu › 6 Analyze Graph › 1 Zero.
5. At lower bound?, type a number to the left of the crossing and press enter. Give the upper bound the same way on the right, and the zero is marked with its coordinates.

Typing the bounds beats clicking them, because you can still see afterwards which interval you searched. The same menu holds 2 Minimum, 3 Maximum, 4 Intersection, 7 Integral and 8 Bounded Area for the region between two curves. With exactly two curves on the page, Intersection and Bounded Area go straight to the bounds.

How do I solve equations on the TI-Nspire CX II?

• Any equation, as a decimal: menu › 3 Algebra › 6 Numerical Solve pastes nSolve(. Type the equation, a comma and the variable: nSolve(2^x=10,x) returns 3.32193. One run finds one solution, so steer it with a starting value: nSolve(x²=2,x=−1) finds −1.41421.
• Polynomials: menu › 3 Algebra › 8 Polynomial Tools › 1 Find Roots of Polynomial… asks for the degree and the coefficients and lists the real roots.
• Linear systems: menu › 3 Algebra › 7 Solve System of Equations › 2 Solve System of Linear Equations… pastes linSolve( with one row per equation.
• Graphically: enter the left side as f1, the right side as f2, and use menu › 6 Analyze Graph › 4 Intersection. This is the only method that shows how many solutions there are.

What does the CAS model add?

CAS stands for computer algebra system. A CX II CAS works with formulas, not only with numbers:

• Derivatives as formulas: menu › 4 Calculus › 1 Derivative. The derivative of 4x²−7x+1 comes back as 8·x−7.
• Factoring: menu › 3 Algebra › 2 Factor turns x²+x−6 into the product of x−2 and x+3.
• Exact solutions: menu › 3 Algebra › 1 Solve rearranges an equation: solve(a·x+b=0,x) gives x=−b/a.
• More: antiderivatives, expanding, tangent lines, limits and differential equations with deSolve.

The CX II without CAS has no symbolic derivative, antiderivative or solve. Its menus offer numerical versions instead, which return a decimal for one x-value, between two limits or near a starting value. Rules for CAS calculators differ between exams, so check your exam rules.

How do I enter data and run statistics?

1. Add a Lists & Spreadsheet page with ctrl doc › 4 Add Lists & Spreadsheet.
2. Type a name into the top cell of a column, then the data below it. Plot pages only list named columns, and the statistics dialogs ask for the name.
3. Press menu › 4 Statistics › 1 Stat Calculations › 1 One-Variable Statistics…, leave Num of Lists at 1 and press enter.
4. Type the column name into X1 List. Press tab until OK is highlighted, then enter; inside a field, enter does not send the dialog.

The results fill two empty columns: mean, standard deviation, count and the five-number summary. 3 Linear Regression (mx+b)… in the same menu fits a line to two named columns and proposes f1 as the place to save it, so it is ready to graph.

What does the TI-Nspire CX II Guidebook cover?

The TI-Nspire CX II Guidebook by Marco Wenisch is intended for use with the TI-Nspire CX II and the TI-Nspire CX II CAS. The 1st Edition has 149 pages and is available as a paperback (ISBN 978-3-69480-023-1) and for Kindle. The paperback has a back-of-book index.

Its nine chapters run from first steps with documents and settings through graphing with sliders and tables, analyzing functions, solving equations, integrals and matrices to statistics with hypothesis tests and confidence intervals. A full CAS chapter follows, and the last one covers Notes, Geometry, Python, the Finance Solver and file transfer. Comparing calculators? See which calculator guide do I need.