How do I use the TI-89 to find the determinants of 3X3 and 4X4 matrices? I only know how to do 2X2, but that would be a waste of time since I can cross multiply.
Well... If you download the Equation Writer program it becomes a lot easier... However, this is a way to input matrices using the calculator alone.
The format is
(the bracket key is located on the comma key (2nd comma) which is immediately left of division):
[[1,2,3][4,5,6][7,8,9]]
This produces a 3x3 like this:
|1 2 3|
|4 5 6|
|7 8 9|
Then you can use the standard matrix operator functions under 2nd Math to find the determinant. For the previous matrix, the determinant would be typed in as follows:
what kind of variable entry are you talking about here? The 89 doesn't seem to do very will with multi-variable stuff (unless you have some programs: implicit differentiation requires a program and some other stuff). Post an example please.
Dave_BerryPosts: 33,350CC Admissions ExpertSenior Member
I mean instead of numbers in the determinant I put in viariables such as a , b, c instead. For 3x3 or 4x4 it says error: non algebvraic variable in expression.
Hi, just registered because I found the solution to this problem. Hopefully it'll help for those people that search for the same problem and have arrived at this thread.
If you get "error: non algebraic variable in expression" that means you have something stored in one of your variables. To fix this, press 2nd, f1, 1, enter.
Replies to: Matrices on the TI-89
The format is
(the bracket key is located on the comma key (2nd comma) which is immediately left of division):
[[1,2,3][4,5,6][7,8,9]]
This produces a 3x3 like this:
|1 2 3|
|4 5 6|
|7 8 9|
Then you can use the standard matrix operator functions under 2nd Math to find the determinant. For the previous matrix, the determinant would be typed in as follows:
2nd -> Math -> det( -> <matrix> -> )
OR
det([[1,2,3][4,5,6][7,8,9]])
2nd-->Math-->Matrix-->newMat(
and then type in the dimensions: newMat(rows, columns)
You get a matrix of all 0's, which you can then replace rather quickly with anything at all.
However, is there any way to compute 4X4 matrices with variables instead of numbers??
If you get "error: non algebraic variable in expression" that means you have something stored in one of your variables. To fix this, press 2nd, f1, 1, enter.
Cheers