# Cramers Rule



## jdd18vm (Aug 13, 2007)

Has anyone actually had to use this on the exam? The calculator is fine for simultaneous equations with 2 or 3 unknowns. But what about for phasor?

For example if you have the following 2 equations

11.59/_15(I1) + 6/_210(I2)=208/_240

6/_210(I1)+10.91/_36.8(I2)=208/_0

I1=23.3/_261 and I2=26.5/_296.4 if interested.

John


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## Flyer_PE (Aug 13, 2007)

John,

I re-taught myself how to do simple matrix operations but I didn't bother with complex numbers. The way I looked at it when studying was that combining complex numbers with matrix operations in one problem would result in something that would take far more than six minutes to solve. There was no indication of something like that in the NCEES sample problems and I didn't encounter it on the exam (April '07, Power Depth). YMMV

Jim


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## Dark Knight (Aug 13, 2007)

jdd18vm said:


> Has anyone actually had to use this on the exam? The calculator is fine for simultaneous equations with 2 or 3 unknowns. But what about for phasor?
> For example if you have the following 2 equations
> 
> 11.59/_15(I1) + 6/_210(I2)=208/_240
> ...


My Casio was able to handle a 2x2 using phasors. I am not sure about yours but it should. I don't know why they took out the 115-ES from the calculators' list. Fudging idiots.


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## jdd18vm (Aug 13, 2007)

Thanks Jim. It seem like it is something that would take some time. I just wasn't sure if its worth taking time to get it. I mean conceptually I do, simple enough, but arduous.

Luis this was from a USF Fehr problem. I'll check out that Casio site just to see if the 155ms does it

John


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## singlespeed (Aug 17, 2007)

You might be able to do a 2 x 2 with complex numbers in 6 minutes without a calculator that handles it. The 115ms *does not* handle complex numbers when in simultaneous equation mode.


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