sundayrose Posted November 24, 2010 Report Share Posted November 24, 2010 I was just wondering if anyone had tips for finding the inverse of a 3x3 matrix.I basically know how to do it using the gauss jordon method i.e. get the identity on the LHS using row operations...but whenever i do this, I always go around in circles.Does anyone have any tips, like whether its best to try and make the numbers all equal to 1 etc.??? Or if a combination of numbers comes up I can do a certain row operation?Thanks, that would be a great help. Reply Link to post Share on other sites More sharing options...
Abu Posted November 24, 2010 Report Share Posted November 24, 2010 Use a calculator? Reply Link to post Share on other sites More sharing options...
sundayrose Posted November 24, 2010 Author Report Share Posted November 24, 2010 No I need to do it by hand. Show my working etc... Reply Link to post Share on other sites More sharing options...
Abu Posted November 24, 2010 Report Share Posted November 24, 2010 Yeah, that was a bit of a cheeky reply. Essentially, you don't need to do it for the syllabus which is why most students on here were probably never taught it. Here's a wikihow article: http://www.wikihow.com/Inverse-a-3X3-Matrix Reply Link to post Share on other sites More sharing options...
CocoPop Posted November 26, 2010 Report Share Posted November 26, 2010 You can find the inverse using LU decomposition. Alternatively, you need to find all of the cofactors of the matrix, which allows you to determine the adjoint. Divide the adjoint by the determinant and you get the inverse. You'll get some pretty good explanations if you Google it, but you definitely don't need to know this for IB... Reply Link to post Share on other sites More sharing options...
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