Solved on Jan 24, 2024

Solve the linear system using Cramer's Rule. Find the determinants DD, DxD_x, and DyD_y. The solution is (x,y)=((x, y) = (DxD\frac{D_x}{D},, DyD\frac{D_y}{D})).

STEP 1

Assumptions
1. We are given a system of linear equations: 3xy=112x+4y=6 \begin{array}{l} -3 x-y=-11 \\ 2 x+4 y=-6 \end{array}
2. We will use Cramer's Rule to solve for xx and yy.
3. Cramer's Rule states that for a system of two linear equations: a1x+b1y=c1a2x+b2y=c2 \begin{array}{l} a_1 x + b_1 y = c_1 \\ a_2 x + b_2 y = c_2 \end{array} the solution can be found using the following formulas, provided that the determinant DD is not zero: x=DxD,y=DyD x = \frac{D_x}{D}, \quad y = \frac{D_y}{D} where DD is the determinant of the coefficient matrix, DxD_x is the determinant of the matrix formed by replacing the xx-coefficients with the constants, and DyD_y is the determinant of the matrix formed by replacing the yy-coefficients with the constants.

STEP 2

Calculate the determinant DD of the coefficient matrix. The coefficient matrix is: (3124) \begin{pmatrix} -3 & -1 \\ 2 & 4 \end{pmatrix} The determinant DD is calculated as: D=(3)(4)(1)(2) D = (-3)(4) - (-1)(2)

STEP 3

Compute the value of the determinant DD. D=(3)(4)(1)(2)=12(2)=12+2=10 D = (-3)(4) - (-1)(2) = -12 - (-2) = -12 + 2 = -10

STEP 4

Calculate the determinant DxD_x by replacing the xx-coefficients with the constants from the right-hand side of the equations. The modified matrix is: (11164) \begin{pmatrix} -11 & -1 \\ -6 & 4 \end{pmatrix} The determinant DxD_x is calculated as: Dx=(11)(4)(1)(6) D_x = (-11)(4) - (-1)(-6)

STEP 5

Compute the value of the determinant DxD_x. Dx=(11)(4)(1)(6)=446=50 D_x = (-11)(4) - (-1)(-6) = -44 - 6 = -50

STEP 6

Calculate the determinant DyD_y by replacing the yy-coefficients with the constants from the right-hand side of the equations. The modified matrix is: (31126) \begin{pmatrix} -3 & -11 \\ 2 & -6 \end{pmatrix} The determinant DyD_y is calculated as: Dy=(3)(6)(2)(11) D_y = (-3)(-6) - (2)(-11)

STEP 7

Compute the value of the determinant DyD_y. Dy=(3)(6)(2)(11)=18+22=40 D_y = (-3)(-6) - (2)(-11) = 18 + 22 = 40

STEP 8

Now that we have the determinants DD, DxD_x, and DyD_y, we can find the values of xx and yy using Cramer's Rule. x=DxD,y=DyD x = \frac{D_x}{D}, \quad y = \frac{D_y}{D}

STEP 9

Calculate the value of xx. x=DxD=5010=5 x = \frac{D_x}{D} = \frac{-50}{-10} = 5

STEP 10

Calculate the value of yy. y=DyD=4010=4 y = \frac{D_y}{D} = \frac{40}{-10} = -4
The solution is (x,y)=(5,4)(x, y) = (5, -4).

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