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Using Cramer's Rule, what is the value of [tex] x [/tex] in the solution to the system of linear equations below?

[tex]\[
\begin{array}{l}
5x - 4 = 3y \\
2x + 32 = 4y
\end{array}
\][/tex]

A. [tex] \frac{1}{12} [/tex]
B. [tex] \frac{2}{3} [/tex]
C. 8
D. 12


Sagot :

To determine the value of [tex]\( x \)[/tex] in the given system of linear equations using Cramer's Rule, we start with these equations:

[tex]\[ 5x - 4 = 3y \][/tex]
[tex]\[ 2x + 32 = 4y \][/tex]

First, we reformulate these equations to standard form [tex]\( Ax + By = C \)[/tex]:

[tex]\[ 5x - 3y = 4 \][/tex]
[tex]\[ 2x - 4y = -32 \][/tex]

Next, we identify the coefficients and constants:
[tex]\[ \begin{aligned} &\text{Coefficients of } x: 5, 2 \\ &\text{Coefficients of } y: -3, -4 \\ &\text{Constants: 4, -32} \end{aligned} \][/tex]

Using Cramer's Rule, we need to calculate the determinants:
[tex]\[ D = \begin{vmatrix} 5 & -3 \\ 2 & -4 \end{vmatrix} \][/tex]
[tex]\[ D_x = \begin{vmatrix} 4 & -3 \\ -32 & -4 \end{vmatrix} \][/tex]
[tex]\[ D_y = \begin{vmatrix} 5 & 4 \\ 2 & -32 \end{vmatrix} \][/tex]

To find [tex]\( D \)[/tex]:
[tex]\[ D = 5(-4) - (-3)(2) \][/tex]
[tex]\[ D = -20 + 6 \][/tex]
[tex]\[ D = -14 \][/tex]

To find [tex]\( D_x \)[/tex]:
[tex]\[ D_x = 4(-4) - (-32)(-3) \][/tex]
[tex]\[ D_x = -16 - 96 \][/tex]
[tex]\[ D_x = -112 \][/tex]

To find [tex]\( D_y \)[/tex]:
[tex]\[ D_y = 5(-32) - 4(2) \][/tex]
[tex]\[ D_y = -160 - 8 \][/tex]
[tex]\[ D_y = -168 \][/tex]

Using Cramer's Rule:
[tex]\[ x = \frac{D_x}{D} = \frac{-112}{-14} = 8 \][/tex]

Thus, the value of [tex]\( x \)[/tex] in the solution to the system of equations is:
[tex]\[ \boxed{8} \][/tex]