Linear Algebra Examples

$[\begin{array}{c} - 2 & 2 & - 6 \\ - 8 & - 9 x & - 18 \\ - 13 & 17 & 7 \end{array}] + [\begin{array}{c} 8 & - 9 & 17 \\ 1 & - 7 & - 16 \\ 5 & - 6 & 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 1

Add the corresponding elements.

$[\begin{array}{c} - 2 + 8 & 2 - 9 & - 6 + 17 \\ - 8 + 1 & - 9 x - 7 & - 18 - 16 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2

Simplify each element.

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Step 2.1

Add $- 2$ and $8$ .

$[\begin{array}{c} 6 & 2 - 9 & - 6 + 17 \\ - 8 + 1 & - 9 x - 7 & - 18 - 16 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.2

Subtract $9$ from $2$ .

$[\begin{array}{c} 6 & - 7 & - 6 + 17 \\ - 8 + 1 & - 9 x - 7 & - 18 - 16 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.3

Add $- 6$ and $17$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 8 + 1 & - 9 x - 7 & - 18 - 16 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.4

Add $- 8$ and $1$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 7 & - 9 x - 7 & - 18 - 16 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.5

Subtract $16$ from $- 18$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 7 & - 9 x - 7 & - 34 \\ - 13 + 5 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.6

Add $- 13$ and $5$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 7 & - 9 x - 7 & - 34 \\ - 8 & 17 - 6 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.7

Subtract $6$ from $17$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 7 & - 9 x - 7 & - 34 \\ - 8 & 11 & 7 + 14 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 2.8

Add $7$ and $14$ .

$[\begin{array}{c} 6 & - 7 & 11 \\ - 7 & - 9 x - 7 & - 34 \\ - 8 & 11 & 21 \end{array}] - [\begin{array}{c} - 6 & - 4 & 1 \\ 20 & 5 & - 17 \\ 13 & 19 & 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 3

Subtract the corresponding elements.

$[\begin{array}{c} 6 + 6 & - 7 + 4 & 11 - 1 \\ - 7 - 20 & - 9 x - 7 - 5 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4

Simplify each element.

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Step 4.1

Add $6$ and $6$ .

$[\begin{array}{c} 12 & - 7 + 4 & 11 - 1 \\ - 7 - 20 & - 9 x - 7 - 5 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.2

Add $- 7$ and $4$ .

$[\begin{array}{c} 12 & - 3 & 11 - 1 \\ - 7 - 20 & - 9 x - 7 - 5 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.3

Subtract $1$ from $11$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 7 - 20 & - 9 x - 7 - 5 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.4

Subtract $20$ from $- 7$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 7 - 5 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.5

Subtract $5$ from $- 7$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 12 & - 34 + 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.6

Add $- 34$ and $17$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 12 & - 17 \\ - 8 - 13 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.7

Subtract $13$ from $- 8$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 12 & - 17 \\ - 21 & 11 - 19 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.8

Subtract $19$ from $11$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 12 & - 17 \\ - 21 & - 8 & 21 - 7 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 4.9

Subtract $7$ from $21$ .

$[\begin{array}{c} 12 & - 3 & 10 \\ - 27 & - 9 x - 12 & - 17 \\ - 21 & - 8 & 14 \end{array}] = [\begin{array}{c} 12 & - 3 & 10 \\ - 27 & 6 & - 17 \\ - 21 & - 8 & 14 \end{array}]$

Step 5

Write as a linear system of equations.

$12 = 12$

$- 3 = - 3$

$10 = 10$

$- 27 = - 27$

$- 9 x - 12 = 6$

$- 17 = - 17$

$- 21 = - 21$

$- 8 = - 8$

$14 = 14$

Step 6

Since $14 = 14$ is always true, the matrix equation has infinite solutions.

Infinite solutions satisfying $- 9 x - 12 = 6$ .