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Question 63037: hello. I would like help on finding the inverse of a 3x3 matrix. my textbook does not explain how to find it.
thank you
Kyle
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! This is one way to do it.
1st: Write down your 3 x 3 matrix which I will call "A".
2nd: Draw a vertical line to the right of the 3rd column.
3rd: Write the 3 x 3 identity matrix to the right of the line
The 1st row of the identity should be to the right of the 1st row of "A".
The 2nd row of the identity should be to the right of the 2nd row of "A"
same for the 3rd row.
4th: Using the Jordan elimination process convert A to the identity matrix
following this rule: "Whatever you do to a row of A do that to the corresponding row to the right"
5th: As "A" becomes the identity matrix, the identity matrix on the right
becomes the inverse of "A".
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Comment: There are other ways to generate A inverse involving determinants,
minors, and co-factors. I will not go into that process.
Also, if you have a scienfic calculator it may have instructions in its manual
which show you how to find the inverse of a matrix.
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Cheers,
Stan H.
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