In-Class Problem 3: Create An Excel Spreadsheet That Will So

In Class Problem 3create An Excel Spreadsheet That Will Solve A Gene

In Class Problem 3: Create an Excel spreadsheet that will solve a general system of 3 linear equations with 3 unknowns. The elements of the matrix should be entered as the cells in rows 1-3 and columns A-D. The spreadsheet should check the answer it generates by computing the right hand side as well. Use the following system as your test case:

3x₁ + x₂ - 2x₃ = 4

- x₁ + 4x₂ + x₃ = 4

- 2x₁ - 2x₂ + 4x₃ = 12

The solution vector is: 4, 4, 4.

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In Class Problem 3create An Excel Spreadsheet That Will Solve A Gene

In Class Problem 3create An Excel Spreadsheet That Will Solve A Gene

Solving systems of linear equations is a fundamental task in mathematics and engineering, often handled with matrix algebra and computational tools such as Excel. The problem at hand involves creating an Excel spreadsheet capable of solving a specific 3x3 system of linear equations with three unknowns, and verifying the computed solution.

The given system is:

  • 3x₁ + x₂ - 2x₃ = 4
  • -x₁ + 4x₂ + x₃ = 4
  • -2x₁ - 2x₂ + 4x₃ = 12

The goal is to set up the spreadsheet such that the coefficients of the variables are inputted in cells A1:D3, with rows corresponding to each equation. The solution vector (x₁, x₂, x₃) should be computed using Excel functions, specifically the MINVERSE and MMULT functions, which allow matrix inversion and multiplication.

Step 1: Input the matrix coefficients

Enter the coefficients of the system in cells as follows:

  • A1: 3, B1: 1, C1: -2
  • A2: -1, B2: 4, C2: 1
  • A3: -2, B3: -2, C3: 4

The right-hand side constants can be entered in cells E1:E3:

  • E1: 4
  • E2: 4
  • E3: 12

Step 2: Calculate the inverse matrix

In cells G1:G3, input the formula `=MINVERSE(A1:C3)` to compute the inverse of the matrix. Since the inverse is a 3x3 matrix, select cells G1:I3 simultaneously, type in `=MINVERSE(A1:C3)` and press Ctrl+Shift+Enter to execute as an array formula. This will populate the 3x3 inverse matrix in G1:I3.

Step 3: Compute the solution vector

Multiply the inverse matrix by the constants vector to find the solution for x₁, x₂, and x₃. Select cells K1:K3, type `=MMULT(G1:I3, E1:E3)` and press Ctrl+Shift+Enter. The results will display the values for the unknowns.

Step 4: Verify the solution

To verify, reconstruct the right side of the equations by multiplying the original matrix by the solution vector:

  • In cells M1:M3, input formulas `=SUMPRODUCT(A1:C1, K1:K3)` for each respective row.

Compare values in M1:M3 with the constants in E1:E3 to check the accuracy. Minor differences may occur due to numerical precision.

Conclusion

This systematic approach in Excel effectively solves the system of equations. The use of matrix functions demonstrates Excel's power in handling linear algebra problems, providing both solutions and verification within a single spreadsheet.

References

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