26 Calculator Keystroke Guide
The value of x in the solution of the system is the top number shown, and the bottom number
shown is the value of y in the solution of the system. Thus, the solution of the system is )1,1(
;
that is, 1 ,1
yx .
page 338
29 Evaluate Y
The TI-82 interprets function notation. Just as for a function xxxR −=
2
4)( the value of the
function when x = −1 can be denoted )1(
R , with the TI-82 the value of Y1 when x = −1 can be
denoted Y1(−1). In the Y= screen enter as Y1 the equation xxy −=
2
4 . Then press 2nd [QUIT] to
return to the Home screen. Press 2nd [Y-VARS] and press ENTER to choose the Function... menu.
Choose Y1 from this menu by pressing ENTER. The calculator returns to the Home screen, and the
variable Y1 will be displayed on the screen. Now type the number −1 in parentheses so that the
expression Y1(-1) is displayed on screen. Press ENTER to see 5, the value of Y1 when x is −1.
To find the value of Y1 when x = 3, press 2nd [ENTRY] to reproduce a copy of Y1(-1), move the
cursor over the -, type a 3, and then press DEL so that the expression reads Y1(3). Press ENTER
to get the value 33. See also 21 Evaluate Y and 22 Table.
page 380
30 Scientific
The TI-82 automatically displays some answers in scientific notation. For example, if you
multiply 658,000 by 240,000, the result is displayed as 1.5792E11. The number following the
E is the exponent of the 10 in scientific notation. Thus, the display should be interpreted as
1.5792·10
11
= 157,920,000,000. Similarly, if you divide 32 by 256,000, the result is displayed as
1.25E
-
4, which means 1.25·10
−4
= .000125.
You may also enter numbers into your calculator in scientific notation. For example, if you
want to enter 3.4·10
7
into your calculator, you would first type in the 3.4. Now press 2nd [EE]. (EE
is the second function on the comma key.) Notice that pressing 2nd [EE] produces the letter E on
the screen to indicate that you are about to enter the power of 10 in scientific notation, which in
this case is 7. After typing the 7, press ENTER, and you will see the number displayed as
34,000,000. It is displayed in standard numeral form, since the number is small enough for the
calculator to display it that way. If you type in a larger number, such as 2.78·10
21
, and press
ENTER, the calculator will still display the number in scientific notation, since the standard
numeral form is too large for the calculator's maximum 10-digit display.
You can also make your calculator display all results in scientific notation, if you wish, by
putting the calculator into Scientific Notation mode. Press the MODE key. There are several
settings that can be changed in the MODE menu, but the first line is our concern here. The word
Normal is probably highlighted in the first line. Use the Right Arrow key to move the blinking
cursor over the word Sci, and press ENTER. The highlight should now disappear from the word
Normal and be on the word Sci. Return to the Home screen by pressing 2nd [QUIT]. Now type the
sum 3 + 9 on the calculator and press ENTER. The result is displayed as 1.2E1, which is
scientific notation for 12. As long as the calculator is in Sci mode, all computation results will be
displayed in scientific notation. To return to the normal display of calculated results, press the
MODE key, and with the blinking cursor on the word Normal, press ENTER. Then press 2nd [QUIT]
to return to the Home screen.
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