Determinant (2x2) - Matrix to Formula

Question

Which shows how to calculate the determinant of this matrix?

$$\left[ {\begin{array} {cc}  -2 &  9 \ -6 &  9 \end{array}  } ight]$$

Accepted Answer

$$(-2 \cdot 9) - (9 \cdot -6)$$

Answer

$$(-2 \cdot 9) - (-6 \cdot 9)$$

Answer

$$(-2 \cdot -6) - (9 \cdot 9)$$

Practice: Matrices - Determinant (2x2) - Matrix to Formula