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January 28th, 2012, 05:40 PM   #1
lkl
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setting up a matrix

we did an economy application problem in class, and i just couldn't figure how the teacher got the final form of the system of equations.

we had a flow chart diagram that shows the percentage of material, labor, and enegry and how much output and input each category receives.

anyways, this was inside my notes:

output = input
Material = .5M + .5L +.6E
Labor = .4M + .3L + .2E
Energy = .1M + .2L + .2E

then he said something about moving everything to the left and ended up with this:
M// .5M - .5L -.6E = 0
L// -.4M - .7L - .2E = 0
E// -.1M - .2L + .8E = 0

so i can't figure out how he got there. he said that .7L was from .4M + .3L which confuse me even more...
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January 28th, 2012, 09:25 PM   #2
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Re: setting up a matrix

Quote:
Originally Posted by lkl
so i can't figure out how he got there..
Neither can I !
Can you post the original problem in full; thank you.
Math requires more than "my notes..." and "he said..."
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January 28th, 2012, 09:30 PM   #3
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Re: setting up a matrix

What i think it is

Material = 1M (total)

so then

Materiel = 1M = 0.5M + 0.5L + 0.6E

Taking it all to the left


1M -0.5M -0.5L-0.6E = 0

Similarly for labour and Energy

Energy = 1.0E (total)

Labour = 1.0L (total)


that's how he got what he did,


hope that helps
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January 29th, 2012, 11:31 AM   #4
lkl
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Re: setting up a matrix

http://i.imgur.com/uTgbA.jpg
http://i.imgur.com/Oqcd9.jpg

those are my notes which is what my teacher wrote on the board. the rest is just row reducing it and solving the system of equations. @grayham1990, i too thought he was moving variables to the left, but i don't know where he would get .7L and .8E in the 2nd and 3rd equation.
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January 29th, 2012, 02:25 PM   #5
lkl
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Re: setting up a matrix

ok nevermind i've figured it out, sort of ignored the decimals so that's why i couldn't see what was happening
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