Test - Texas Instruments TI-82 Keystroke Manual

18 Calculator Keystroke Guide
Y . Enter as Y the expression
1 2
see all three graphs displayed. Press the TRACE key to activate the Trace cursor. The Trace cursor
will appear on the graph of Y
straight-line graph, the graph of Y
keys to trace along the graph of Y
press the Down Arrow key again. Move the Left and Right Arrow keys to trace along the graph of
Y . If you press the Down Arrow key once more, the Trace cursor will cycle back to the graph of
3
Y . (If four graphs were displayed, the Trace cursor would have moved to the graph of the fourth
1
equation.) Pressing the Up Arrow key makes the Trace cursor move from graph to graph in
reverse order. While the Trace cursor is on, try pressing the Up Arrow key a few times to see how
the Trace cursor moves from graph to graph.
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24 Test

The items on the TEST menu may be used to tell whether a relationship between two numbers or
expressions is true or false. To see how it works, let's let the calculator verify something you
already know: 7 is less than 8. At the Home screen type a 7 and then press 2nd [TEST] (the second
function on the MATH key) to produce the TEST menu. The "less than" symbol < is choice 5 on the
menu. Either press 5 or use the Down Arrow key to highlight the 5 and press ENTER. The <
symbol will appear on the Home screen after the 7. Then type an 8, so that the Home screen now
shows 7<8. You want to know if this statement is true. The calculator will tell you when you
press ENTER. The calculator will display a 1 if the statement is true or a 0 if the statement is false.
In this case, of course, the calculator displays a 1, since 7 is less than 8.
Now let's enter a false statement: 4 > 11. Type a 4 and then press 2nd [TEST] to produce the
TEST menu. The "greater than" symbol > is choice 3 on the menu, so press 3 to produce the >
symbol on the Home screen after the 4. Now type 11 and press ENTER. The calculator displays a
0 to tell you that the statement is false.
Next let's try one that perhaps isn't so obvious. Is
division key ÷ to produce the diagonal slash division sign /) and press ENTER to find out. The
statement is false, since the calculator responds with a 0.
The TEST menu may also be used to test proposed solutions of equations. For example, to test
whether 2 is a solution of the equation
Then type in the equation
menu.) Since the calculator displays the value 1 (true), 2 is a solution of the equation. Using the
same method, test whether –2 is a solution of the equation
the value of x and then type in the equation, the calculator should display the value 0 (false) when
you press ENTER, indicating that –2 is not a solution of the equation. Note: This approach to
testing solutions of equations is reliable only for exact solutions. Rounded solutions or other
approximate solutions usually do not test as correct.
− x 2 −
11 . Enter as Y
, as it did before. To make the Trace cursor move to the other
1
, press the Down Arrow key. Move the Left and Right Arrow
2
. To make the Trace cursor move to the curved graph of Y
2
− x = −
1 3 5
− x = −
and press ENTER. (Note that "=" is choice 1 on the TEST
1 3 5
2
x
−
the expression
3
5
>
5 59
? Type in 5/8 > 59/93 (using the
8 93
, first store 2 as the value of x. (See 14 Store.)
+ = −
. After you store –2 as
2 x 5 1 x
. Press GRAPH to
18
,
3