 ### graphing calculator use -- page 1

Take the absolute value
Change a decimal to a fraction
You CAN'T COMBINE LIKE TERMS
Compute with fractions
Store a constant (or perhaps an expression)
Evaluate an expression
Raise a number to a power

## The Absolute Value of a Number, |x|

The first function an algebra I student encounters is absolute value, or distance from zero. When written in symbols it looks like: |x|. When used on a calculator, it looks like: abs(x). Ex 1.
1st: Press the ABS or the abs( button.
TI82: Press [2nd] then [x-1], (left column) for ABS.
TI83 or the TI85, in the NUM (for number), abs(
2nd: Type the number and the right parenthises, ).
3rd: Press ENTER to execute the command.

## Compute with Fractions

Each fraction is really a division waiting to be completed. The division combined with order of operations, and parenthises as inclusion marks makes any fraction computation possible.

Ex 1. Write 4/5 as a decimal.
Type 4/5 and press [ENTER].
The result is .8 or 0.8.

You might wish to undo the division and change this into a fraction using the calculator.

Ex 2. Simplify 4/5 + 2/3
Type 4/5 + 2/3, press [ENTER]
Type (4/5) + (2/3), press [ENTER].

Ex 3. Simplify 2 4/5 + 2/3
Type (2 + 4/5) + 2/3, press [ENTER], or,
Type 2 + 4/5 + 2/3, press [ENTER].

Ex 4. Simplify 2 4/5 - 1 2/3
Type 2 + 4/5 - (1 + 2/3), press [ENTER], or,
Type (2 + 4/5) - (1 + 2/3), press [ENTER].

## Change a deciaml to a fraction

The FRAC button permits the user to change many decimal numbers to a fraction representation of that number. Ex 1. A decimal number is displayed on the home screen.
1st: Press the FRAC button located on the:
TI82 or the TI83, in the MATH, 1: FRAC
TI85, in the MISC (for miscellaneous), FRAC
2nd: Press ENTER to execute the command.

## STO or store

STO permits the user to store a constant value, or in more sophisticated machines, a variable expression in the calculator so that its value may be saved or used.

Ex 1. Store the number 2 in the storage location named x
1st: Type 2 on the display.
2nd: Press the STO key.
3rd: Press the X key
The calculator displays:
2 STO X
4th: Press ENTER to execute the command and the 2 appears on the display.

Ex 2. Store the number 2 in the storage location named A
1st: Type 2 on the display.
2nd: Press the STO key.
3rd: Press the ALPHA then A.     The color of the ALPHA key is the same as the color of the printing of the letters above the keys.
The calculator displays:
2 STO A
4th: Press ENTER and the 2 appears on the display.

## Evaluate an expression

Once a value has been stored, it may be used to evaluate an expression.

Ex. Evaluate 2x when x is 6 1st: Type 6 on the display.
2nd: Press the STO key.
3rd: Press the X key or ALPHA then X.
(The color of the ALPHA key is the same as the color of the printing of the letters above the keys.)
4th: Press ENTER and the 6 appears on the display.
5th: Type 2x on the display.
6th: Press ENTER and 12 appears on the display
because 2(6) is 12.

## You CAN'T COMBINE LIKE TERMS

Unless the calculator has symbol manipulation capabilities like the HP38, HP48, TI89, TI92, it can not combine like terms.

You can evaluate an expression like
2x + 3(x + 1) + 6x - 8 for a specific value of x.

You can not simplify 2x + 3(x + 1) + 6x - 8 as
2x + 3x + 3 + 6x - 8 or finally 11x - 5.

There is no way to store the value of x as x. Ordinary graphing calculators do not accept symbols as variable values.

## Raise A Number to A Power

The caret, ^ , or the y-to-the-x, yx, or the x-to-the-y, xy, is used to exponentiate or raise to a power.

Ex 1. Simplify 32.
Type 3 ^ 2 and press [ENTER].
The result is 9.         © 2007, Agnes Azzolino,   www.mathnstuff.com/math/algebra/acalcu1.htm