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Graphing Calculator: Home Screen
For simple computations, a graphing calculator works just like a scientific one. As soon as you want to combine computations, the graphing calculator gains an advantage. A graphing calculator follows order of operations when performing a computation. For example:

12 + 36 ÷ 6 ´ 5 - 1 = 41

can be done simply by typing in the problem as it is given. Try this problem now on your calculator and make sure you get 41 as your answer.

Using a scientific calculator, you would have to go through the order of operations yourself before getting help from the calculator.

Try these three problems to see if you get the correct answer.
4 ´ 6 ÷ 2 +50 ÷ 10 ´ 3 = 27
34 - 15 ÷ 5 ´ 2 = 75
53 + (18 - 14)2´ 3 = 173
Evaluating trigonometric functions also works differently than on a scientific calculator. Again, you simply enter the problem into the calculator as it is given.

sin(30º) = 0.5

Make sure your calculator is in degree mode. If you need help with setting the mode, take a moment and reference the calculator mode lesson.

Notice that ( automatically appears on the TI-83 when you use certain functions. This is not the case with all graphing calculators. If you are using a different model, you may not see parentheses appear on your screen unless you type them in yourself.

Also notice that the degree symbol does not appear on your screen. So it is important that the mode setting be correct.

Try these problems to make sure you are getting the correct answers. All problems are in degrees.
sin(143º) = 0.6018150232
tan(45º) = 1
cos(60º) = 0.5
With an answer of 0.5 on your screen, you can utilize another feature of the calculator. Press the key. The first option under the MATH menu is Frac. This will change a decimal into a fraction. Press once and you’ll see the command pasted onto your home screen. Press again and the calculator will change 0.5 into 1/2.

Try changing these decimals into fractions.

The key has four menus with many options within each menu. We will only discuss three of these options. For more information on the other features, consult your user’s guide.

To find the absolute value of an expression on the home screen or to graph an absolute value function, you must press the key and use the right arrow key to get to the NUM menu. The first option there is abs, the absolute value. Pressing once pastes the abs command on the home screen along with an open parentheses. The calculator is waiting for you to input a number or expression.
abs(-3) = 3
abs(-3 + 8 ´ 5 -50) = 13
Under the MATH menu from the key, you can evaluate cube root or nth root expressions. To find , press , then use the key to go to option 4. Pressing pastes the cube root command on the home screen and the calculator is awaiting your input. Enter and then press . The answer of –3 should appear on the screen.

Note that there is a difference between the "negative" key and the "subtraction" key. The negative key is used when indicating the opposite or the negative of a number. It is located between the decimal point key and the key. The subtraction key is used to indicate an operation on two numbers. It is located on the far right side of the calculator between the multiplication key and the addition key. When working with either of the keys, if you encounter a syntax error, you have most likely used the wrong key.

When evaluating you can also make use of the laws of exponents to rewrite as and obtain the answer directly from the keypad and home screen without having to utilize any menus. Use the key to enter the exponent. Also, the parentheses are absolutely necessary for both the –27 and the 1/3. Remember that the calculator uses order of operations in evaluating your input. Without the parentheses, the calculator would raise 27 to the first power, divide that answer by 3, and then change the sign. You can see from the screen below, this is not the answer we are looking for.

Roots higher than 3 can be evaluated similarly on the home screen or from the MATH menu. Option 5 under the MATH menu requires a different set of keystrokes from a cube root. To evaluate , you must press . This set of key strokes indicates that you want a fourth root (4), takes you to the MATH menu (MATH), chooses the nth root option (5), enters the number 64 on your home screen (64) and evaluates the answer (ENTER).

Other keys to note are:
Evaluating square roots:
Find reciprocals:
Raising e to a power:

As a concluding exercise, try evaluating these expressions to make sure that you can get the correct answer given.

S Taylor

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