Texas Instruments TI-92 Getting Started page 7

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Graphing Technology Guide: TI-92

Figure 5.9: Complex number calculations

The TI-92 can also solve for the real and complex roots of an equation. This is done by using the cSolve( function

which is not on any of the keys, but can be found in the CATALOG. From the Home screen, pressing 2nd

CATALOG gives an alphabetical list of all functions and operations available on the TI-92. You can scroll through

the CATALOG page-by-page by pressing 2nd

, or if you know what letter the function starts with, pressing the

letter moves the cursor to the beginning of the listings for that letter.

The format of cSolve( is cSolve(expression, variable). For example, to find the zeros of f (x) = x

– 4x

+ 14x –

20, from the Home screen press 2nd CATALOG and move the cursor down to cSolve(, then press ENTER. The

display will return to the Home screen, with cSolve( on the entry line. To complete the computation, press X ∧ 3 –

4 X ∧ 2 + 14 X – 20 = 0 , X) ENTER. The TI-92 will display the real and complex roots of the equation, as shown

in Figure 5.10.

Figure 5.10: cSolve function

All functions and commands found in the CATALOG, can also be used by merely typing the command using the

keyboard. Hence, in the Home screen, you could also press C S 0 L V E (X ∧ 3 – 4 X ∧ 2 + 14 X – 20 = 0 , X)

ENTER to find the zeros of f(x) = x

– 4x

+ 14x – 20.

5.2 Functions and Graphs

5.2.1 Evaluating Functions: Suppose you receive a monthly salary of $1975 plus a commission of 10% of sales.

Let x = your sales in dollars; then your wages W in dollars are given by the equation W = 1975 + .10x. If your

January sales were $2230 and your February sales were $1865, what was your income during those months?

Here's one method to use your TI-92 to perform this task. Press the

Y= key (above the letter W) or APPS 2[Y=

Editor] to display the function editing screen (Figure 5.11). You may enter as many as ninety-nine different

functions for the TI-92 to use at one time. If there is already a function y1 press

as many times as necessary

to move the cursor to y1 and then press CLEAR to delete whatever was there. Then enter the expression 1975 +.

10x by pressing these keys: 1975 + .1 0 X ENTER. Now press

HOME.