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Solving a System of Three Linear Equations Using Cramer's Rule

To solve a system of three linear equations with three variables using Cramer's Rule, the procedure is similar to solving a system of two equations, but requires evaluating 3×33 \times 3 determinants. Follow these seven steps: 1. Evaluate the main determinant DD, using the coefficients of the variables. 2. Evaluate the determinant DxD_x by using the system's constants in place of the xx coefficients. 3. Evaluate the determinant DyD_y by using the system's constants in place of the yy coefficients. 4. Evaluate the determinant DzD_z by using the system's constants in place of the zz coefficients. 5. Find the values of xx, yy, and zz using the formulas x=DxDx = \frac{D_x}{D}, y=DyDy = \frac{D_y}{D}, and z=DzDz = \frac{D_z}{D}. 6. Write the final solution as an ordered triple (x, y, z). 7. Check that the ordered triple is a valid solution by substituting it back into all three original equations.

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Updated 2026-07-02

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Ch.4 Systems of Linear Equations - Intermediate Algebra @ OpenStax

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