Course Software

This is an amortization table and matrix program
created by Brooks/Cole publishing company (publishers of *Mathematics: A Practical
Odyssey*).

Using Amortrix to compute amortization schedules:

Follow the directions in the program. The most important thing is to be sure to enter the money and percents in the right formats. Once you have generated the amortization schedule, follow the procedure below to make a printout of the months you want.

- Open a new word document.
- Get into Amortrix, and calculate the amortization schedule.
- Use the mouse to high-light the months of the amortization schedule that you want to print.
- Press control-c to copy what you have high-lighted.
- Switch to the word document and click on where you want to insert the table.
- Press control-v to paste the amortization schedule into the word document.
- Print the word document as usual.
- Don't forget to put your name and the section/problem number on each page!!!!

Using Amortrix to solve systems of equations with matrices:

Your answers should consist of :

- the solution to the system. You can copy the Matrix into a Word document by typing Alt-PrintScreen (hold down the Alt key while you press the PrintScreen key).
- a list of the row operations used in the order in which you used them,

For example:

- Divided row 1 by 5.2
- Added –2.5 times the top row to the middle row
- Added 42 times the top row to the bottom row
- Switched the middle and the bottom row, etc.

- the work you did (using your calculator) to check your answers.

Here is how to manipulate the program:

To get leading 1’s:

- Click on the bad row for the entry in the "1
^{st}row" box - Copy the bad number (using Ctrl-c to copy and Ctrl-v to paste) into the "enter constant" box.
- Click on "divide".

To get 0’s:

- Click on the tool row for the entry in the "1
^{st}row" box. - Click on the bad row for the entry in the "2
^{nd}row" box.

- Copy the bad number (using Ctrl-c to copy and Ctrl-v to paste) into the "enter constant" box.

- Change the sign of the bad number by placing the cursor in front of it and either deleting or inserting the minus sign.
- Enter the location of the bad row
*by typing it in*(the program will mess up if you try to do this by clicking) in the "enter a row number" box. - Click on Multiply.Add.

Because of rounding off, you might get a number like 0.9999 or 1.0001 where you expect to get a 1. This is Ok. There is a similar problem with the numbers close to zero. The numbers with "e" in them are just scientific notation for teeny tiny numbers, eg 7 e -6, means 7 times 10^(-6), so if you get these numbers, it means that they are practically zero, except that the computer is rounding off.

This program will NOT let you save your work. You may want to occasionally cut (with Alt-PrintScreen) and paste your work into a Word document, so that you can copy the numbers off it in case something messes up. This way you won’t have to redo the whole problem. You can reenter the numbers you had already gotten, and will only have to go from there.

** **

Solve:

3x – 2y = 11

4.32x + 6.2y =-3.23

First enter the matrix

Now divide the top row by 3 to get a leading 1:

The result is:

Now get a zero below the 1 by adding –4.32 times the top row to the bottom row:

The result is:

Now get a leading 1 in the second row by dividing it by 9.08:

The result is:

Now get a zero above the 1 by adding +0.66666667 times the bottom row to the top row:

The result is:

And now you know that the answer is: x = 2.26652 and y = -2.10022.

What to turn in:

You would turn in a copy of this last picture.

You would turn in the following list:

- Divided top row by 3 to get a leading 1.
- Added –4.32 times the top row to the bottom row.
- Got a leading 1 in the second row by dividing it by 9.08.
- Added +0.66666667 times the bottom row to the top row.

You would turn in the following showing how you checked your work:

x = 2.26652 and y = -2.10022 ü

3(2.26652 ) – 2(-2.10022) = 6.79956 + 4.20044 = 11 ü

4.32(2.26652 ) + 6.2(-2.10022) = 9.7913664 – 13.021364 = - 3.2299976 ü

the answer here is just a tiny bit off from – 3.23 because of rounding, but this is close enough!