Matrices

matrix

a rectangular arrangement of numbers

dimensions of a matrix

m rows and n columns; m × n (read "m by n")

elements

the numbers in a matrix

scalar

a real number

scalar multiplication

to multiply a matrix by a scalar, multiply each element in the matrix by the scalar

Cramer's Rule

using determinants to solve a system of linear equations

identity matrix

a matrix with ones for all elements on the main diagonal (top left to bottom right) and zeros for all the other elements

inverse matrices

two n x n matrices A and B whose product is the n x n identity matrix; AB = I and BA = I