http://www.math.ncsu.edu:8370/ma114/tools/row_ops.html

We are supposed to use this tool to solve for:

1. Use the row operations tool to solve the following system of equations, obtaining the solutions in fraction form:
8x + 2y + z = 4
3x + 3y - 4z = 5
2x - 2y + 4z = 1
Give the values for x, y, and z with the fractions reduced to lowest terms (for example 4/7 rather than 8/14):
x = , y = , z =

and

2. Use the row operations tool to solve the following system of equations, obtaining the solutions in fraction form:
7x + 9y + 4z = 8
5x + 9y + 10z = 1
2x + 4y + 8z = -5
3x + 5y + 2z = 6
4x + 4y + 2z = 2
Give the values for x, y, and z with the fractions reduced to lowest terms (for example 1/2 rather than 3/6):
x = , y = , z =

How the hell does this thing work?

1/24/2006 11:26:30 PM

did you try plugging in the matrix?

i havent used that tool since.. approx 2001? so its been a while, but i just plugged in some numbers now..

8 2 1 4
3 3 -4 5
2 -2 4 1

in the slots for x1-x4. .. then you can either Reduce Completely, or you can try and do it yourself by highlighting a number and pivoting on that point.



Edit: Basically it just seems like a nifty little tool for you to check that you're understanding how to do matrices w/o being bogged down w/ all the writing and potential calculation errors midroute. Also it's a good way to check matrices you do by hand later.. work out the problem, then plug it in and see if you got the right answer.

[Edited on January 24, 2006 at 11:35 PM. Reason : Goodnight.. im out.]

1/24/2006 11:33:55 PM

Plug in the coeffients for each of the equation in seperate rows

8 2 1 4
3 3 -4 5
2 -2 4 1

The use the row operation tool to reduce the rows to
1 0 0 A
0 1 0 B
0 0 1 C

Once you are done A=x, B=y, and C=z

Do the same for the next question but you only need to put in 3 equations

1/25/2006 11:11:20 AM

straight up... use your matrix on your calculater.. so much easier

1/25/2006 11:32:44 AM

Most professors for that course do expect you to be able to do some simple examples by hand, so don't do all the problems with the built in matrix tool. Otherwise you'll be hurting at test time.

1/25/2006 5:45:11 PM

u cant take an inverse with a ti-83 can u?

1/26/2006 2:56:13 PM

I think TI-83 will rref of ref right? So you could make the matrix [A|I] and row rref it to get
[I|B] (assuming A is invertible) the matrix B will be the inverse of A.

Of course, I forget there may be a direct command on the TI-83, but I think not.

1/26/2006 6:41:14 PM

The teacher specifically asked on WebAssign to do certain problems with that tool. I have never used it before. I would much rather do them on paper!

1/26/2006 7:35:22 PM

maybe he/she thought they'd be easier with the tool. Personally I avoid anything bigger than 3x3 if I can, it's just hard to do that much arithmatic w/o messing something up somewhere. I bet he/she was just trying to save you guys some trouble with the harder problems. If you can do them on paper quickly and correctly more power to you.

1/27/2006 12:01:47 AM

i'll do this tomorrow when i wake up if no one else has answered it

[Edited on January 27, 2006 at 1:56 AM. Reason : easy class]

1/27/2006 1:56:08 AM