# Ti-89 Titanium Solving equation systems

• May 3rd 2008, 06:18 AM
armin
Ti-89 Titanium Solving equation systems
I've got the following two source equitations:
1.
(c*ucde + ((l*ilde) + uc)/r + (l*ilde + uc - us)/r) = 0
2.
(-c*ucde + il + (alfa*(l*ilde + uc)/r)) = 0

I'm looking for a symbolic solution in the following format:
ucde -> -((-2 il r - alfa us)/((2 + alfa) c r))
ilde -> -((il r + 2 uc + alfa uc - us)/((2 + alfa) l))
How sholud i enter this question on my Ti-89 Titanium.

The jpg file contains the solution in the mathematica program, but i need the solution on my TI.89 titanium.
• May 3rd 2008, 06:21 AM
Moo
Hello,

I think you should do this way (but I'm not sure because I don't know what these letters represent) :

solve(first equation and second equation, [x,y])

where x and y are the variables.

I put it initially, but it seems that it doesn't look useful without it... I don't know what ilde and ucde represent. But if you're dealing with variables containing more than one letter in their name, I advice you to change their names into single letters.
• May 3rd 2008, 09:56 AM
armin
This is what I typed into my TI89:

solve((c*ucde + ((l*ilde) + uc)/r + (l*ilde + uc - us)/r) = 0 and (-c*ucde + il + (alfa*(l*ilde + uc)/r) = 0, [ucde,ilde])

This is what I got:
Error: Argument must be a variable name

What am I doing wrong?
• May 3rd 2008, 09:57 AM
Moo
Is ucde a name or u*c*d*e ?

Because your calculator will understand it as u*c*d*e
• May 3rd 2008, 10:04 AM
armin
Sorry

solve((c*ucde + ((l*ilde) + uc)/r + (l*ilde + uc - us)/r) = 0 and (-c*ucde + il + (alfa*(l*ilde + uc)/r) )= 0, [ucde,ilde])
• May 3rd 2008, 10:05 AM
armin
ucde, ilde, uc are variable names.
• May 3rd 2008, 10:26 AM
armin
IT WORKS!

Thank you very match!!!