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Solve any four.

Solve the system of equations using Cramer's Rule:
[tex]\[ y + 2x - 19 = 0 \][/tex]
[tex]\[ 2x - 3y + 3 = 0 \][/tex]


Sagot :

Sure, let's solve the given system of linear equations using Cramer's Rule.

The system of equations is:
[tex]\[ \begin{cases} y + 2x - 19 = 0 \\ 2x - 3y + 3 = 0 \end{cases} \][/tex]

First, rearrange the equations to the standard form [tex]\(ax + by + c = 0\)[/tex]:

1. [tex]\(2x - 3y + 3 = 0\)[/tex]
2. [tex]\(2x + y - 19 = 0\)[/tex]

We can extract the coefficients from these equations:
[tex]\[ \begin{cases} a_1 = 2, \quad b_1 = -3, \quad c_1 = 3 \\ a_2 = 2, \quad b_2 = 1, \quad c_2 = -19 \end{cases} \][/tex]

Cramer's Rule uses determinants to solve for [tex]\(x\)[/tex] and [tex]\(y\)[/tex]. First, we need to find the determinant [tex]\(D\)[/tex] of the coefficient matrix:
[tex]\[ D = \begin{vmatrix} a_1 & b_1 \\ a_2 & b_2 \end{vmatrix} = \begin{vmatrix} 2 & -3 \\ 2 & 1 \end{vmatrix} \][/tex]

Calculating [tex]\(D\)[/tex]:
[tex]\[ D = (2 \cdot 1) - (2 \cdot -3) = 2 + 6 = 8 \][/tex]

Next, we find the determinant [tex]\(D_x\)[/tex] by replacing the first column of the coefficient matrix with the constants from the right side of the equations:
[tex]\[ D_x = \begin{vmatrix} c_1 & b_1 \\ c_2 & b_2 \end{vmatrix} = \begin{vmatrix} 3 & -3 \\ -19 & 1 \end{vmatrix} \][/tex]

Calculating [tex]\(D_x\)[/tex]:
[tex]\[ D_x = (3 \cdot 1) - (-19 \cdot -3) = 3 - 57 = -54 \][/tex]

Then, we find the determinant [tex]\(D_y\)[/tex] by replacing the second column of the coefficient matrix with the constants from the right side of the equations:
[tex]\[ D_y = \begin{vmatrix} a_1 & c_1 \\ a_2 & c_2 \end{vmatrix} = \begin{vmatrix} 2 & 3 \\ 2 & -19 \end{vmatrix} \][/tex]

Calculating [tex]\(D_y\)[/tex]:
[tex]\[ D_y = (2 \cdot -19) - (2 \cdot 3) = -38 - 6 = -44 \][/tex]

Using Cramer's Rule, we can now solve for [tex]\(x\)[/tex] and [tex]\(y\)[/tex]:
[tex]\[ x = \frac{D_x}{D} = \frac{-54}{8} = -6.75 \][/tex]
[tex]\[ y = \frac{D_y}{D} = \frac{-44}{8} = -5.5 \][/tex]

Therefore, the solution to the system of equations is:
[tex]\[ x = -6.75, \quad y = -5.5 \][/tex]

These are the values of [tex]\(x\)[/tex] and [tex]\(y\)[/tex] that satisfy both equations.