TI-84 CALCULATOR GUIDE

Find zeros on a TI-84

Use 2nd → TRACE → zero to find both roots of a quadratic on a physical TI-84. Choose separate left and right bounds and resolve NO SIGN CHANGE.

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Graph a functionFix the windowFind roots

These three guides cover function graphing, viewing windows and graph zeros. Key names are shown as printed on the calculator; screen layouts can vary with software versions.

Before you start: function mode

Press MODE. Use the arrow keys to select FUNC (Func on some versions) and press ENTER. Press 2nd, then MODE (QUIT) to leave the menu. These examples use ordinary function graphing. Preserve any work you need before changing entries or settings.

Solve an equation with its graph

0 of 5 steps marked done

  1. 1

    Graph the expression that should equal zero

    Y=X,T,θ,n

    In Y=, use an unused enabled line to enter X² − 5X + 6. Preserve your existing work and turn unrelated functions and Plot labels off. For an equation L = R, graph L − R instead.

    What you should see

    Your enabled Y line contains X² − 5X + 6.

  2. 2

    Choose a useful window

    WINDOWGRAPH

    In WINDOW, set Xmin = 0, Xmax = 5, Xscl = 1, Ymin = −1, Ymax = 7 and Yscl = 1. Use (-) to enter −1. Press GRAPH.

    What you should see

    A parabola crosses the x-axis near X = 2 and X = 3.

  3. 3

    Open the zero tool

    2ndTRACE2:zero

    Press 2nd, then TRACE to open CALC. Choose 2:zero. If more than one function is enabled, use the up/down arrows to select the intended curve.

    What you should see

    The calculator asks for Left Bound?.

  4. 4

    Find the first root

    1.5ENTER2.5ENTER2ENTER

    For Left Bound?, type 1.5 and press ENTER. For Right Bound?, type 2.5 and press ENTER. For Guess?, type 2 and press ENTER. These bounds isolate the first crossing in this example.

    What you should see

    A zero near X = 2, with Y = 0. Numerical output may be approximate.

  5. 5

    Find and check the other root

    2ndTRACE2:zero

    Repeat 2nd → TRACE → 2:zero with left bound 2.5, right bound 3.5 and guess 3, pressing ENTER after each value. Substitute both results into the original equation. Other equations need different windows and bounds.

    What you should see

    The second zero is near X = 3. Both 2 and 3 satisfy X² − 5X + 6 = 0.

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TI reference material

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How to Find Zeros on a TI-84 Plus & Plus CE | HowSolve