Kirchhoff's Law: Solving Matrix Inverse on HP 48GX

AI Thread Summary
The discussion focuses on using the HP 48GX calculator to solve Kirchhoff's Law equations involving matrix inverses. The user is attempting to compute the inverse of a 3x3 matrix related to current and voltage equations but encounters issues with the calculator not allowing the operation. Despite trying various methods, the results differ from classmates using TI 3600 calculators. The user eventually realizes the solution to their problem was simpler than anticipated. Additionally, there is a brief mention of converting decimals to fractions, which was not the main focus of the discussion.
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This is more of a calculator problem, we are currently doing Kirchhoff's Law in class and we are using the equation [A]^-1 x [X], where A is a 3x3 matrix containing the I3=I1+I2 and the V Rise and V Drop equations and the X is a matrix of the voltage values.
Ex.(I1)=(I2)+(I3) Loop 1= 12=(I1)5+(I2)4+10 Loop 2= (I3)2=10+(I2)4
0=-I1+I2+I3 0=(I1)5+(I2)4+10-12 0=10+(I2)4-(I3)2
[[-1 1 1] ^-1 [[ 0 ]
[ 5 4 0] x [ 2 ]
[ 0 4 -2]] [-10]]
But herein lies my problem, I have an HP 48GX, and it will not allow me to take the inverse of the first equation. I tried to take the inverse of each individual number as i entered it into the matrix, but the answer that i derived was not the same as those of my fellow classmates, all of whom are using TI 3600's. So how would i go about fixing this problem. And on a smaller note, is it possible to convert a decemile into a fraction? Thanx.
 
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