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    Hey guys,

    I have the following to solve:

    (12*10^5)a + (6*10^5)b + (6*10^5)c = -1000

    (6*10^5)a + (4*10^5)b + (2*10^5)c = 0

    (6*10^5)a + (2*10^5)b + (8*10^5)c = 500

    I keep solving by using the first equation to get a as the subject, then sub that in to 2 and make b the subject then finally sub all in to 3 to solve.

    The answers (rounded) should be a=-0.0058, b=0.0075 and c=0.0025

    Can anyone help as I keep getting:

    b=0.00875 and c=0.00375

    thanks
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    How about: Add the second to the third, then subtract the first to eliminate 'a' and 'b' at the same time...
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    yeh that is easier.

    Am I doing something wrong though because I am still getting 0.00375 instead of 0.0025?
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    (Original post by Big_Sam)
    yeh that is easier.

    Am I doing something wrong though because I am still getting 0.00375 instead of 0.0025?
    I agree with you: c = 0.00375.
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    yeh but its a past exam paper and the answers should be the ones in the op
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    (Original post by Big_Sam)
    yeh but its a past exam paper and the answers should be the ones in the op
    Well then either the equations you've got have a mistake in them/are different to the ones in the actual paper, or the answers are wrong...
 
 
 
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