Easy Practice — Set 2

Quick Recap — Determinants

• $\begin{vmatrix}a&b\\c&d\end{vmatrix}=ad-bc$; a triangular/diagonal determinant is the product of the diagonal.
• Singular matrix: $\det=0$; invertible iff $\det\ne0$.
• $|A^T|=|A|$, $|AB|=|A||B|$, $|kA|=k^n|A|$ for $n\times n$.
• Interchanging two rows flips the sign; two equal rows/columns give $\det=0$.