Sample_simple_set_of_simultaneous_equations

Sample_simple_set_of_simultaneous_equations - 5 Pick one of...

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Example of how to solve simultaneous equations using Excel J. M. Cimbala, August 2005 Consider the following set of 3 simultaneous equations for 3 unknowns, a, b, and c: 3a + b - 2c = 4 4a - 3b + 2c = 0 2a - 4c = 5 Although it is not necessary, it is usually good practice to re-write the equations such that the right hand side of each equation is zero: 3a + b - 2c - 4 = 0 4a - 3b + 2c = 0 2a - 4c - 5 = 0 To solve the set of equations, we set up cells for the values of a, b, and c, and we set up cells for the right-hand sides (RHS) of each equation. In addition, we set up 3 cells called "Solver cells", as shown below: a b c RHS Solver cells 0.64 0.23 -0.93 0 0 0 0 0 0 To solve: 1 2 Enter guesses for a, b, and c (typically guess 1, 1, and 1) 3 Enter the right hand side values of each equation (0, 0, and 0) 4 In the "Solver cells" column, enter the LHS equations, one for each equation, as indicated above. Note: Use the cell indices in the equations. E.g., the first equation is "=3*A22+B22-2*C22-4".
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Unformatted text preview: 5 Pick one of the Solver cells (I picked the first one) as the "Target Cell" in the Solver feature of Excel: a. Highlight the first Solver cell b. c. Set the value of this cell equal to the value of the RHS for that particular equation (zero). d. Set "By Changing Cells" to the cell indices of variables a, b, and c. e. Set the constraints such that the other two Solver cells must equal their respective RHS: i) ii) The Solver window for this example should look like the image below. f. 6 If all goes well, the Solver cells should equal the RHS cells respectively, and the values of a, b, and c will automatically adjust to their final iterated correct values. Tools-Add-Ins-Solver Add-in-OK Tools-Solver Click Add , and then construct two equations as the constraints. Solve and then OK ....
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