Equivalent Matrices

Two matrices are considered equivalent if they share the same solution set, S, for their associated linear systems.

Example
Illustrating equivalent matrices

The equivalence of two matrices, M and M', is denoted by the tilde symbol (~).
Notation for equivalent matrices

Example

Matrices are often used to represent systems of linear equations.

Example: Matrix and its associated system of equations

Reordering the equations in a linear system does not alter the solution set.

Example: Systems of equations

Likewise, changing the row order in a matrix produces an equivalent matrix.

Example: Two equivalent matrices

Note: This is a simplified example for clarity. In practice, equivalent matrices may have entirely different values for their elements. Several methods exist for matrix transformations, with Gaussian elimination and Gauss-Jordan elimination being the most widely used.
Another example of equivalent matrices

Constructing an Equivalent Matrix

Using Gaussian elimination, any matrix M can be transformed into an equivalent matrix M' through a sequence of permitted operations, known as Gaussian moves.

  1. Interchanging rows in the matrix
    Notation and example of row interchange between two matrices
  2. Multiplying a row by a nonzero real number α
    An example of the second allowable Gaussian move
  3. Adding corresponding elements from two rows
    Summing two rows in the matrix
    If two polynomials have a shared root, that root will remain in the sum. Therefore, the solutions of the original polynomials are also solutions in their sum.

Note: These operations can also be applied in combination. For example, a row may be added to another row multiplied by a real number.

 
 

Please feel free to point out any errors or typos, or share suggestions to improve these notes. English isn't my first language, so if you notice any mistakes, let me know, and I'll be sure to fix them.

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Matrices (linear algebra)