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Re: Missing link


Manuel,

sys = {{1, 3, 2, 3}, {-3, 1, 4, 1}, {5, 7, 2, b}};  X = Array[x,
Length[sys]]; 
sysTr = Transpose[sys]; 
eqns = Transpose[Drop[sysTr, -1]].X == Last[sysTr]

{x[1] + 3*x[2] + 2*x[3], -3*x[1] + x[2] + 4*x[3], 
   5*x[1] + 7*x[2] + 2*x[3]} == {3, 1, b}

Solve[eqns, b]

{{b -> 7}}

Bob Hanlon

In a message dated 5/30/98 8:47:53 PM, MAvalosJr at AOL.com wrote:

>Is there a way to find in a system of linear equations the numerical
>value of a symbol,say,b. The example below is easy enough with pencil
>and paper but some matrices get a little too complicated and would like
>to find a method with mathematica.
>
>Suppose the matrix is {{1,3,2,3},{-3,1,4,1},{5,7,2,b}}.  b must have the
>value of 7 in order the system have a solution. 


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