Here is how to work with multiple unknow.
This comes from one of J.Walk's old newsletter - they are still worth
reading.

Ola Sandström



POWER FORMULA TECHNIQUE

By Alab Beban

Here is an example of how to solve a set of simultaneous equations
using
Excel.

Start with equations that are linearly independent so that there is,
in fact, a solution; e.g.,

17 = 5x + 3y + 2z
13 = 2x + 4y + z
22 = 3x + 2y + 5z

Put the coefficients of the unknowns in, e.g., A1:C3 (i.e., 5,3,2 in
A1:C1, 2,4,1 in A2:C2, etc.);

Put the constants (17, 13, 22) in, e.g., D1:D3;

Highlight, e.g., E1:E3 and array enter (i.e., enter with
Ctrl+Shift+Enter instead of just Enter)

=MMULT(MINVERSE(A1:C3,D1:D3)

and the solution vector (1,2,3) will appear in E1:E3;
i.e., x=1, y=2, z=3

For a set of equations that does not have a solution, the #VALUE error
will appear in E1:E3.


--
olasa
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