Types

System of Equations
At least two linear equations in more than two variables.
5x + 3y - 8z = 11
-x + 7y = 10
9x + z = 0

Coefficient Matrix
A matrix consisting of the coefficients of the terms from a system of equations.
Coefficient Matrix

Augmented Matrix
A matrix consisting of the coefficients and constants of the terms from a system of equations.
Augmented Matrix

Side by side comparison





Equal Matrices
Two matrices are equal iff they have the same dimensions and are identical, element by element.
Two Equal Matrices
So, A = B.

Zero Matrix aka Identify Matrix for Addition
A matrix whose entries are all zeros.
Zero Matrix                     Zero Matrix                         Zero Matrix

Square Matrix
A matrix whose number of rows and columns are equal.  A square matrix can also be called a matrix of the nth order (n being the size of the matrix)
Square Matrix of 3rd order

Identity Matrix for Multiplication
A matrix whose entry in the first row and first column is a 1, and entry in the second row and second column is a 1, and whose entry in the third row and third column is a 1, etc.  All other entries are 0s.
Identity Matrix for Multiplication

Row-Echelon Form
A matrix is in row echelon form if

  1. Rows consisting entirely of zeros (if any) appear at the bottom of the matrix
  2. The first entry in a row with nonzero entries is 1, called a leading 1.
  3. For two consecutive rows with nonzero entries, the leading 1 in the higher row is farther to the left than the leading 1 in the lower row.
Row-echelon form
Row-echelon form

Notice in each example, the triangular nature of the nonzero entries.


Reduced Row-Echelon Form
A matrix is in row reduced echelon form if the following conditions are satisfied:
  1. The first nonzero element in each row (if any) is a "1" (a leading coefficient).
  2. Each leading coefficient is the only nonzero element in its column.
  3. All the all-zero rows (if any) are at the bottom of the matrix.
  4. The leading coefficients form a "stairstep pattern" from northwest to southeast




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