Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Determinants

Question:

The system of equations 3x + 4y = 5, 6x + 7y = -8 is written in matrix from as

Options:

$\left[\begin{array}{ll}3 & 4 \\ 6 & 7\end{array}\right]\left[\begin{array}{ll}x & y\end{array}\right]=\left[\begin{array}{ll}5 & -8\end{array}\right]$

$\left[\begin{array}{ll}3 & 6 \\ 4 & 7\end{array}\right]\left[\begin{array}{l}x \\ y\end{array}\right]=\left[\begin{array}{c}5 \\ -8\end{array}\right]$

$\begin{bmatrix} 3 & 4 \\ 6 & 7 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 5 \\ -8 \end{bmatrix}$

$\left[\begin{array}{ll}x & y\end{array}\right]\left[\begin{array}{ll}3 & 6 \\ 4 & 7\end{array}\right]=\left[\begin{array}{ll}5 & -8\end{array}\right]$

Correct Answer:

$\begin{bmatrix} 3 & 4 \\ 6 & 7 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 5 \\ -8 \end{bmatrix}$

Explanation:

The correct answer is Option 3: $\begin{bmatrix} 3 & 4 \\ 6 & 7 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 5 \\ -8 \end{bmatrix}$

Let the system be:

$\begin{cases} 3x + 4y = 5 \\ 6x + 7y = -8 \end{cases}$

Matrix form

A system of linear equations can be written as:

$AX = B$

where

$A = \begin{bmatrix} 3 & 4 \\ 6 & 7 \end{bmatrix}, \quad X = \begin{bmatrix} x \\ y \end{bmatrix}, \quad B = \begin{bmatrix} 5 \\ -8 \end{bmatrix}$

Hence, the matrix form is:

$\begin{bmatrix} 3 & 4 \\ 6 & 7 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 5 \\ -8 \end{bmatrix}$