Linear Algebra Examples

$[\begin{array}{c} 4 & - 7 & 4 \\ 0 & - 3 & 4 \\ 0 & - 8 & 9 \end{array}] - [\begin{array}{c} 4 & 0 & 0 \\ 0 & 4 & 0 \\ 0 & 0 & 4 \end{array}]$

Step 1

Subtract the corresponding elements.

$[\begin{array}{c} 4 - 4 & - 7 - 0 & 4 - 0 \\ 0 - 0 & - 3 - 4 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2

Simplify each element.

Tap for more steps...

Step 2.1

Subtract $4$ from $4$ .

$[\begin{array}{c} 0 & - 7 - 0 & 4 - 0 \\ 0 - 0 & - 3 - 4 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.2

Subtract $0$ from $- 7$ .

$[\begin{array}{c} 0 & - 7 & 4 - 0 \\ 0 - 0 & - 3 - 4 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.3

Subtract $0$ from $4$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 - 0 & - 3 - 4 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.4

Subtract $0$ from $0$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 3 - 4 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.5

Subtract $4$ from $- 3$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 7 & 4 - 0 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.6

Subtract $0$ from $4$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 7 & 4 \\ 0 - 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.7

Subtract $0$ from $0$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 7 & 4 \\ 0 & - 8 - 0 & 9 - 4 \end{array}]$

Step 2.8

Subtract $0$ from $- 8$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 7 & 4 \\ 0 & - 8 & 9 - 4 \end{array}]$

Step 2.9

Subtract $4$ from $9$ .

$[\begin{array}{c} 0 & - 7 & 4 \\ 0 & - 7 & 4 \\ 0 & - 8 & 5 \end{array}]$

Step 3

Choose the row or column with the most $0$ elements. If there are no $0$ elements choose any row or column. Multiply every element in column $1$ by its cofactor and add.

Tap for more steps...

Step 3.1

Consider the corresponding sign chart.

$| \begin{array}{c} + & - & + \\ - & + & - \\ + & - & + \end{array} |$

Step 3.2

The cofactor is the minor with the sign changed if the indices match a $-$ position on the sign chart.

Step 3.3

The minor for $a_{11}$ is the determinant with row $1$ and column $1$ deleted.

$| \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$

Step 3.4

Multiply element $a_{11}$ by its cofactor.

$0 | \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$

Step 3.5

The minor for $a_{21}$ is the determinant with row $2$ and column $1$ deleted.

$| \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$

Step 3.6

Multiply element $a_{21}$ by its cofactor.

$0 | \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$

Step 3.7

The minor for $a_{31}$ is the determinant with row $3$ and column $1$ deleted.

$| \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$

Step 3.8

Multiply element $a_{31}$ by its cofactor.

$0 | \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$

Step 3.9

Add the terms together.

$0 | \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} | + 0 | \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} | + 0 | \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$

Step 4

Multiply $0$ by $| \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$ .

$0 + 0 | \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} | + 0 | \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$

Step 5

Multiply $0$ by $| \begin{array}{c} - 7 & 4 \\ - 8 & 5 \end{array} |$ .

$0 + 0 + 0 | \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$

Step 6

Multiply $0$ by $| \begin{array}{c} - 7 & 4 \\ - 7 & 4 \end{array} |$ .

$0 + 0 + 0$

Step 7

Simplify the determinant.

Tap for more steps...

Step 7.1

Add $0$ and $0$ .

$0 + 0$

Step 7.2

Add $0$ and $0$ .

$0$