4.1 Types of Matrices
Row
Column
Square
Diagonal
Scalar
Identity
Zero
Symmetric
Skew-Symmetric
4.2 Matrix Operations
Addition
Scalar multiplication
Multiplication (AB possible only if columns of A = rows of B)
4.3 Determinants
2×2
∣abcd∣=ad−bc\begin{vmatrix} a & b\\ c & d \end{vmatrix} = ad - bcac
bd=ad−bc
3×3
Use cofactor expansion.