Algebra Examples

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

These are both valid notations for the determinant of a matrix.

$determinant [\begin{array}{c} 9 & 8 \\ 7 & 8 \end{array}] = | \begin{array}{c} 9 & 8 \\ 7 & 8 \end{array} |$

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$(9) (8) - 7 \cdot 8$

Simplify the determinant.

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Simplify each term.

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Multiply $9$ by $8$ .

$72 - 7 \cdot 8$

Multiply $- 7$ by $8$ .

$72 - 56$

Subtract $56$ from $72$ .

$16$