Ti-84 Plus Graphing Calculator For Dummies, 2nd Edition
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You can use your TI-84 Plus calculator to evaluate a definite integral, which gives the area between the curve and the x-axis. For example, if f(x) is positive for

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also gives the area between the curve and the x-axis for

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To evaluate the definite integral, perform the following steps:

  1. Graph the function f(x) in a viewing window that contains the Lower Limit a and the Upper Limit b.

    To get a viewing window containing a and b, these values must be between Xmin and Xmax.

  2. Press [2nd][TRACE] to access the Calculate menu.

  3. Press [7] to select the following option:

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  4. If necessary, repeatedly press the up- and down-arrow keys until the appropriate function appears in the border at the top of the screen.

    This process is illustrated in the first screen.

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  5. Enter the value of the Lower Limit a.

    To do so, use the keypad to enter the value of the Lower Limit a. As you use the keypad, X= appears, replacing the coordinates of the cursor location appearing at the bottom of the screen in Step 4. The number you key in appears after X=. This is illustrated in the second screen. If you make a mistake when entering your number, press [CLEAR] and re-enter the number.

  6. Press [ENTER].

    After pressing [ENTER], a Left Bound indicator (the dotted line with a triangular indicator) appears on the graphing screen.

  7. Enter the value of the Upper Limit b and press [ENTER].

    After pressing [ENTER], the value of the definite integral appears in the border at the bottom of the screen and the area between the curve and the x-axis will be shaded. This is illustrated in the third screen. The TI-84 Plus C uses interval notation to display the interval of the definite integral.

The shading of the graph produced by using the

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option on the Calculate menu doesn't automatically vanish when you use another Calculate option. To erase the shading, press [2nd][PRGM][ENTER] to invoke the ClrDraw command on the Draw menu. The graph is then redrawn without the shading.

About This Article

This article is from the book:

About the book authors:

Jeff McCalla is a mathematics teacher at St. Mary's Episcopal School in Memphis, TN. He cofounded the TI-Nspire SuperUser group, and received the Presidential Award for Excellence in Science & Mathematics Teaching. C.C. Edwards is an educator who has presented numerous workshops on using TI calculators.

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