# Practice: Expressing Linear Equations As Matrices

 1. Express the following set of linear equations as a matrix. \begin{align} 2x + 4y = 6 \\ 2x + 6y = 8 \end{align} solution $\begin{bmatrix} 2 & 4 \\ 2 & 6 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 6 \\ 8 \end{bmatrix}$ 3. Express the following set of linear equations as a matrix \begin{align} 4a - b = 4 \\ 5a - 2b = 2 \\ a + 3b = 4 \end{align} solution $\begin{bmatrix} 4 & -1 \\ 5 & -2 \\ 1 & 3 \end{bmatrix} \begin{bmatrix} a \\ b \end{bmatrix} = \begin{bmatrix} 4 \\ 2 \\ 4 \end{bmatrix}$ 2. Express the following set of linear equations as a matrix \begin{align} 2x_1 + x_2 + 7x_3 = 5 \\ x_1 + x_2 + 5x_3 = 3 \end{align} solution $\begin{bmatrix} 2 & 1 & 7 \\ 1 & 1 & 5 \end{bmatrix} \begin{bmatrix} x_1 \\ x_2 \\ x_3 \end{bmatrix} = \begin{bmatrix} 5 \\ 3 \end{bmatrix}$