Wize University Linear Algebra Textbook > Matrices
Matrix Inverse Algorithm
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Matrix Inverse Algorithm
Matrix Inverse ()
The inverse of a matrix can be found using the following formula:
Note: a matrix is invertible if and only if .
Example
Find the inverse of .
Matrix Inverse (Any Size)
Use Gauss-Jordan elimination to row reduce into . Applying the same EROs to will give us !
Steps
- Augment the matrix with : Example ():
- Use Gauss-Jordan elimination to row reduce to , creating the matrix: Example ():
Wize Tip
If cannot be row reduced to , then does not exist, i.e. is not invertible.

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Example: Matrix Inverse Algorithm
Find the inverse of using the formula for a matrix, and using the Gauss-Jordan elimination algorithm.
Using the Formula
Using the Algorithm
Note: You can always check your answer.

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Example: Matrix Inverse Algorithm
Find the inverse of the matrix , if it exists.
Since we were able to reduce into , the inverse exists and .
Exercise: check if and .
Mark Yourself Question
- Grab a piece of paper and try this problem yourself.
- When you're done, check the "I have answered this question" box below.
- View the solution and report whether you got it right or wrong.
Find the inverse of the matrix .