Algebra Beispiele

$[\begin{array}{c} - 4 & 1 & 2 \\ - 1 & 0 & - 2 \\ 5 & 0 & 1 \end{array}]$

Schritt 1

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 $2$ by its cofactor and add.

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Schritt 1.1

Consider the corresponding sign chart.

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

Schritt 1.2

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

Schritt 1.3

The minor for $a_{12}$ is the determinant with row $1$ and column $2$ deleted.

$| \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} |$

Schritt 1.4

Multiply element $a_{12}$ by its cofactor.

$- 1 | \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} |$

Schritt 1.5

The minor for $a_{22}$ is the determinant with row $2$ and column $2$ deleted.

$| \begin{array}{c} - 4 & 2 \\ 5 & 1 \end{array} |$

Schritt 1.6

Multiply element $a_{22}$ by its cofactor.

$0 | \begin{array}{c} - 4 & 2 \\ 5 & 1 \end{array} |$

Schritt 1.7

The minor for $a_{32}$ is the determinant with row $3$ and column $2$ deleted.

$| \begin{array}{c} - 4 & 2 \\ - 1 & - 2 \end{array} |$

Schritt 1.8

Multiply element $a_{32}$ by its cofactor.

$0 | \begin{array}{c} - 4 & 2 \\ - 1 & - 2 \end{array} |$

Schritt 1.9

Add the terms together.

$- 1 | \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} | + 0 | \begin{array}{c} - 4 & 2 \\ 5 & 1 \end{array} | + 0 | \begin{array}{c} - 4 & 2 \\ - 1 & - 2 \end{array} |$

Schritt 2

Mutltipliziere $0$ mit $| \begin{array}{c} - 4 & 2 \\ 5 & 1 \end{array} |$ .

$- 1 | \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} | + 0 + 0 | \begin{array}{c} - 4 & 2 \\ - 1 & - 2 \end{array} |$

Schritt 3

Mutltipliziere $0$ mit $| \begin{array}{c} - 4 & 2 \\ - 1 & - 2 \end{array} |$ .

$- 1 | \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} | + 0 + 0$

Schritt 4

Berechne $| \begin{array}{c} - 1 & - 2 \\ 5 & 1 \end{array} |$ .

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Schritt 4.1

Die Determinante einer $2 \times 2$ -Matrix kann mithilfe der Formel $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ bestimmt werden.

$- 1 (- 1 \cdot 1 - 5 \cdot - 2) + 0 + 0$

Schritt 4.2

Vereinfache die Determinante.

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Schritt 4.2.1

Vereinfache jeden Term.

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Schritt 4.2.1.1

Mutltipliziere $- 1$ mit $1$ .

$- 1 (- 1 - 5 \cdot - 2) + 0 + 0$

Schritt 4.2.1.2

Mutltipliziere $- 5$ mit $- 2$ .

$- 1 (- 1 + 10) + 0 + 0$

Schritt 4.2.2

Addiere $- 1$ und $10$ .

$- 1 \cdot 9 + 0 + 0$

Schritt 5

Vereinfache die Determinante.

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Schritt 5.1

Mutltipliziere $- 1$ mit $9$ .

$- 9 + 0 + 0$

Schritt 5.2

Addiere $- 9$ und $0$ .

$- 9 + 0$

Schritt 5.3

Addiere $- 9$ und $0$ .

$- 9$