Texas Instruments TINSPIRECX manual History Lesson, Approximate Calculations

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First Steps with TI-Nspire™

Tutorial 2: The Calculator Application

A History Lesson

You will have noticed that, as new expressions are entered, previous ones scroll off the top of the screen. The TI-Nspire handheld will remember a history of up to 99 expressions and these can be recalled using the up key on the Touchpad. Press and hold £ and see the way the highlight flicks back through previous expressions and results. Stop at some point in the history and press ·. You should see either the previous expression or the result copied to the entry line ready to be used as all or part of a new expression.

Notice that, after an expression has been evaluated, simply pressing · again repeats the previous entry. What would you expect to see if you repeatedly pressed · on this screen? Try it by pressing

1· lv1¢+1

···…

Notice how entering an operation at the beginning of an expression (the power operation in this example) causes the automatic entry of Ans, standing for the previous answer.

If you ever need to clear the history there is an option in the Actions submenu: press b15. This is also a way of producing an uncluttered screen for making screenshots such as the one above.

Approximate Calculations

If you repeat the key sequence above but replace the first · with /· you get the rather different results shown here. Try it and continue pressing · until you get an (apparently) unchanging approximation for the Golden Ratio.

The default mode for calculations is to give exact results (using fractions) rather than approximate results (using decimals). It is possible to alter this using the system settings as you will see later in this tutorial.

Another way of choosing a decimal result is to enter a decimal

in the expression that you type, e.g. try entering 1 / 7 and then 1.0 / 7.

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© 2012 Texas Instruments Education Technology

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Contents First Steps About this document Contents Appendix TI-Nspire CX Keypad Layout Nothing on the screen? TI-Nspire DocumentsMemory Battery Life Charging the handheldHome Screen First Steps with TI-Nspire Tutorial 1 TI-Nspire documents Documents, Problems and Pages ScratchpadNavigating Documents First Steps with TI-Nspire Tutorial 1 TI-Nspire documents Contextual Menus Check list of some key points in Tutorial Calculator Application Basic operationsHistory Lesson Approximate CalculationsTemplates Menu of maths templatesEffect of changed settings Document settings dialog boxGetting Set Ways to define variables Some AlgebraUse of function notation Statistical Distribution Tables Calculator MenuLists of random integers Variables Linked to Documents List of defined variablesMaking Notes Why use Notes?Various text formatting Instructions Recording results Format sub-menu Splitting the ScreenWays to split the screen You must press /e and then b An inserted comment Use of proof template and symbols More Options from the Notes MenuInteractive Notes Use of Q+A templateAsking Questions Check list of some key points in Tutorial Graphing Graphs & Geometry Two ViewsGraphing Functions Graphing ViewGrab and Drag Practice Changing the AxesOpen-hand cursor Grabbed tick mark on the axesEditing, Deleting or Hiding a Function Zoom settings Grabbed-sheet iconChanging f2 in the function history Tracing Graphs Points and coordinatesTrace picks out significant points Points of intersectionAnalyse Graph Menu Coordinates and labelled pointsManually Moving Graphs Using SlidersAlternative icons Transformed graph and equation Sequence Plotting Check list of some key points in Tutorial Geometry View for Plane GeometryTwo Parallel Lines Drawing the base of the triangleConstruct the Triangle What’s grabbable?Many options in the Construction menu Making Measurements Variables and TextMeasurement menu Storing the measurement as a variableTidying Up and Using Attributes Dynamic ChangesReady to grab a and slide it Changing the attributes of the triangleArea is now locked Unlocked/Unpinned Points B and C. Try Moving point BCheck list of some key points in Tutorial Lists & Spreadsheet Entering Data as ListsConflict resolution Using FormulaeOne way to enter a formula Typical Spreadsheet Actions Function Tables Capturing DataHand-made function table Simple function table Options for function tables Graph and table side by sideFrequency Charts One and Two Variable Statistics Charts with One VariableShoe Sizes and Hand Spans Charts for Categorical Data Pie Chart displaying categorical dataComparing Boxplots Upper quartile displayedFitting a Line by Hand and Eye Charts with Two VariablesReady to add a 2nd variable Getting the Stats Drawing the Regression LineCalculated regression line Statistics Calculations menu Dragging on the Charts Working with Frequency DataSets of statistics Effect of moving a point from here … … to hereTexas Instruments Education Technology Check list of some key points in Tutorial Draw and Measure a Circle Multiple RepresentationsMeasured circle Setting up a scatter plot Data capture is under way Spreadsheet for Data CaptureTwo Scatterplots Collecting Just a Little DataGo to Town with Data Collection Fit a Straight LineLinear relationship Moving a straight line by hand Not a linear relationshipRegression Different Approach to ScatterplotsBasic quadratic ready for fitting… … and dragged into place