Matrices (ACT) Basic Operations Addition/Subtraction: add/subtract corresponding elements (same dimensions required) Scalar multiplication: multiply every element by the scalar Matrix multiplication: dot product of rows and columns 2×2 Determinant det([a b; c d) = ad - bc] ACT Tips Matrix multiplication is NOT commutative (AB ≠ BA generally) Dimensions: (m×n) × (n×p) = (m×p) The ACT tests basic operations more than advanced matrix theory