I know how to compute determinants using cofactor expansion and row operations. But what does the determinant actually **represent geometrically**?
For a $2 \times 2$ matrix $A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}$, $\det(A) = ad - bc$. What does this number tell us about the transformation represented by $A$? And how does this generalise to $3 \times 3$ and higher dimensions?