Solving Simultaneous
Equations on a TI-89
(One of many possible methods!)
1) Start with your equations:
5y + 3z = 1
3x – 3z + 3y = 2
2z + 4x – 7y = 6
2) Rearrange the equations so the
variables are in the same order:
5y + 3z = 1
3x – 3z + 3y = 2
2z + 4x – 7y = 6
x
0
3
4
y
5
3
-7
z answer
3
1
-3
2
2
6
3) Select the rref function (reduced
row echelon form):
1.
2.
3.
4.
5.
Press 2nd
Press 5 (MATH)
Press 4 (Matrix)
Press 4 (rref)
Alternative – Press CATALOG,
press alpha then 2, find rref
4) Enter the matrix values into your
calculator:
Use the format:
[[0,5,3,1][3,3,-3,1][4,-7,2,6]]
Each set of brackets corresponds
with one row
Note: No spaces, only commas!
5) Find your solution!
1. Put the right parenthesis
after the matrix
2. Hit enter!
3. Your answer for each
variable is the entry in the
same row with a one in the
column of your variable, in
this case:
x = 1.169
y = -0.063
z = 0.439
Other TI calculators, other methods
• All TI graphing calculators
should have the rref
function
• Some calculators have the
simult function – use two
matrices, one for
variables and one for
answers
• The solve function can
also be used on some
calculators – this is more
complex to enter
• RREF on the TI-83
• RREF on the TI-84 (all
editions)
• Another method, TI-89
and TI-92
• A third method, TI-89
• Entering Matrices, TI-83
and TI-84
• Matrix Operations, TI-89