Chapter 1 Section 0 Example 1 on the TI-83

Note that the TI-83 and the TI-83 plus have slightly different keys. This page uses the keys associated with the TI-83. The differences are that the TI-83 key is replaced by the TI-83 Plus key, and the TI-83 key is replaced by the TI-83 Plus key.

The first Example in the text asks us to evaluate

E =

(x – y)(xy + z)

(zy – 2x)

when x=2, y=^–1/2 and z=^–3

On the calculator we can do this by assigning values to variables X, Y, and Z, and then entering the expression to evaluate. The following sequence of screen images and comments trace such steps.

Figure 1

We will start by assigning the value 2 to the variable X. We press

to produce Figure 1.

Figure 2

We press the

key to get the calculator to actually do the command. The calculator acknowledges that assignment with a 2 on the right side of the next line.

Figure 3

We will continue by storing ^–1/2 into Y via the keys

NOTE: we use the key to change the sign of a value and we use the for subtraction. Do not confuse these two keys.

Also, we need to reference the variable Y by pressing the key to shift the calculator into "alpha" mode before we press the to select the "Y".

And we assign ^–3 to Z via

. This should leave the screen as in Figure 3.

Figure 4

Now, all we need to do is to enter the desired expression, namely

(X – Y)(XY + Z)

(ZY – 2X)

We note that the expression contains the implied multiplication of X and Y (in XY), of Z and Y (in ZY) and of 2 and X (in 2X). The TI-83 calculator does not need to be told of the multiplication between the variables. This implied multiplication on the TI-83 is acceptable because variables on the TI-83 can be at most one character long. Even though the implied multiplication is acceptable, we will include the multiplication operator between variables, that is we will type X*Y for XY. Therefore, we construct the expression as in Figure 4 via the keys

. We note that when the input line gets too long the calculator merely moves to the next line.

In addition, notice that we could refernce the variable X either via the

key or via the two key sequence

Figure 5

In Figure 5 we have pressed the

to perform the calculation and we see the result, 4, displayed at the right of the screen.