The problem asks us to find the value of $x$ given the matrix equation: $$ \begin{bmatrix} 6 & -2 \\ -7 & 4 \end{bmatrix} \begin{bmatrix} 2 \\ 3 \end{bmatrix} = \frac{1}{3x} \begin{bmatrix} 36 \\ -12 \end{bmatrix} $$

AlgebraLinear AlgebraMatrix OperationsMatrix MultiplicationSolving Equations
2025/5/9

1. Problem Description

The problem asks us to find the value of xx given the matrix equation:
[6274][23]=13x[3612] \begin{bmatrix} 6 & -2 \\ -7 & 4 \end{bmatrix} \begin{bmatrix} 2 \\ 3 \end{bmatrix} = \frac{1}{3x} \begin{bmatrix} 36 \\ -12 \end{bmatrix}

2. Solution Steps

First, we perform the matrix multiplication on the left side:
[6274][23]=[(6)(2)+(2)(3)(7)(2)+(4)(3)]=[12614+12]=[62] \begin{bmatrix} 6 & -2 \\ -7 & 4 \end{bmatrix} \begin{bmatrix} 2 \\ 3 \end{bmatrix} = \begin{bmatrix} (6)(2) + (-2)(3) \\ (-7)(2) + (4)(3) \end{bmatrix} = \begin{bmatrix} 12 - 6 \\ -14 + 12 \end{bmatrix} = \begin{bmatrix} 6 \\ -2 \end{bmatrix}
So the equation becomes:
[62]=13x[3612] \begin{bmatrix} 6 \\ -2 \end{bmatrix} = \frac{1}{3x} \begin{bmatrix} 36 \\ -12 \end{bmatrix}
This means:
6=363x 6 = \frac{36}{3x}
2=123x -2 = \frac{-12}{3x}
We can use either equation to solve for xx. Let's use the first equation:
6=363x 6 = \frac{36}{3x}
Multiply both sides by 3x3x:
18x=36 18x = 36
Divide both sides by 18:
x=3618=2 x = \frac{36}{18} = 2
Now, let's check if the second equation gives the same result:
2=123x -2 = \frac{-12}{3x}
Multiply both sides by 3x3x:
6x=12 -6x = -12
Divide both sides by -6:
x=126=2 x = \frac{-12}{-6} = 2
Both equations give the same result, x=2x=2.

3. Final Answer

The value of xx is 2.

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