Arman G. answered • 11/10/19
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New to Wyzant
Aerospace Engineer
Form the augmented matrix [1 3 7 12; 1 4 10 15; 2 3 5 x] and keep row reducing. Eventually you should get the bottom row is [ 0 0 0 X+c] where c is some constant. This could only be true if x = c, whatever that constant is that you get by row reduction
Arman G.
The comment didn't keep my formatting, I meant to space out the numbers in a matrix
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11/10/19
Arman G.
hint: you should get x between 14 and 17... but that's what's required for the system to be consistent
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11/10/19
Michael A.
Can you help explain how I get wha the values for xyz are. I assume I keep reducing but I don’t seem to get 000 x+c
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11/11/19
Arman G.
I think you posted the same problem twice and in the second answer I listed my row reduction steps (R2 =R2-R1, R3 = R3-2*R1 and then R3 = R3+3*R2) and you should get [0 0 0 x-15] so x has to equal 15 so that b3 can row reduce to zero when you finish row reducing, z is a free variable, so x and y are written in terms of z. you get x = 2z+3, y = -3z+3, z = 3. so you have to be given z, if z is 7 then x is 17, y is -18. This is the only solution that will satisfy x + 3y + 7z = 12, if z has to equal 7. This, therefore does not represent a physical system like you've described because you cant have negative 18 pieces of bread.
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11/11/19
Arman G.
if the way i wrote the matrix is confusing, the ';' just means next row 1, 3, 7, 12 1, 4, 10, 15 2, 3, 5, X also you said it's a 3x4 matrix, but really A is a 3x3 and it's only the augmented matrix that's a 3x411/10/19