Example

Example: Solving a System of Two Equations Using Cramer's Rule

Solve the system {2x+y=−43x−2y=−6\left\{\begin{array}{l} 2x + y = -4 3x - 2y = -6 \end{array}\right. using Cramer's rule. First, evaluate the determinant DD using the coefficients of the variables: D=∣213−2∣=(2)(−2)−(1)(3)=−7D = \begin{vmatrix} 2 & 1 3 & -2 \end{vmatrix} = (2)(-2) - (1)(3) = -7. Next, evaluate DxD_x by replacing the xx coefficients with the constants −4-4 and −6-6: Dx=∣−41−6−2∣=(−4)(−2)−(1)(−6)=14D_x = \begin{vmatrix} -4 & 1 -6 & -2 \end{vmatrix} = (-4)(-2) - (1)(-6) = 14. Then, evaluate DyD_y by replacing the yy coefficients with the constants: Dy=∣2−43−6∣=(2)(−6)−(−4)(3)=0D_y = \begin{vmatrix} 2 & -4 3 & -6 \end{vmatrix} = (2)(-6) - (-4)(3) = 0. Now, find xx and yy using the formulas: x=DxD=14−7=−2x = \frac{D_x}{D} = \frac{14}{-7} = -2 and y=DyD=0−7=0y = \frac{D_y}{D} = \frac{0}{-7} = 0. Write the solution as the ordered pair (−2,0)(-2, 0). Finally, check the solution in both original equations to verify it is correct.

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Updated 2026-06-17

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