find inverse by row transformation matrix 3 x 3 [1 2 3 -1 1 2 1 2 4]
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https://www.meritnation.com/ask-answer/question/using-elementary-row-transformation-find-the-inverse-of-the/matrices/10516789
https://www.meritnation.com/ask-answer/question/find-the-inverse-using-elementary-transformation-4-3-3/matrices/1771507