December 28th, 2016, 04:27 PM  #1 
Newbie Joined: Dec 2016 From: Canada Posts: 5 Thanks: 0  Matrix problem
I have a matrix that needs solving to open a Christmas present. Does anyone know how . I have not used that math for forty years and by coincidence I threw that text away only two months ago. Here is a link to the problem. Only one of the three is actually needed to open this box puzzle thing. This is part of an ongoing game that we have played for a number of years. This box might hold another bottle of 18 yr old Bowmore Islay single malt and I could "share" https://drive.google.com/drive/folde...mc?usp=sharing Any help would be greatly appreciated Thanks Norm 
December 28th, 2016, 07:01 PM  #2 
Senior Member Joined: Dec 2012 From: Hong Kong Posts: 763 Thanks: 278 Math Focus: Linear algebra, linear statistical models 
You need, for example, to combine A and b together to form an augmented matrix, then apply Gaussian elimination and find the column vectors. The presentgiver apparently expects you to use the inverse matrix method for these, though it's a bit cumbersome to do that with these matrices, since there's no shortcut formula for 4x4 
December 28th, 2016, 07:49 PM  #3 
Newbie Joined: Dec 2016 From: Canada Posts: 5 Thanks: 0 
My soninlaw was going to be even tougher but it has been 10 years since his masters so he thought he would be " kind". It has been 40 years for me.

December 28th, 2016, 08:01 PM  #4 
Senior Member Joined: Sep 2015 From: CA Posts: 595 Thanks: 319  
December 29th, 2016, 07:39 AM  #5 
Newbie Joined: Dec 2016 From: Canada Posts: 5 Thanks: 0 
Whoop hoo Worked like a charm. Thanks very much Norm 
December 30th, 2016, 12:37 PM  #6 
Senior Member Joined: Sep 2015 From: CA Posts: 595 Thanks: 319  
December 31st, 2016, 10:24 PM  #7 
Newbie Joined: Dec 2016 From: Canada Posts: 5 Thanks: 0 
And I, kind sir, would be happy to pour you a wee dram. However there was but a lone bottle of beer....Innis & Butt...or something. If your ever out Victoria BC way then stop by for a cold one or eleven! Thanks again Norm Would you care to see the box that was opened? Last edited by Nheagle; December 31st, 2016 at 10:32 PM. 
December 31st, 2016, 11:46 PM  #8 
Senior Member Joined: Feb 2016 From: Australia Posts: 725 Thanks: 271 Math Focus: Yet to find out.  
January 1st, 2017, 08:35 AM  #9 
Newbie Joined: Dec 2016 From: Canada Posts: 5 Thanks: 0 
A few pics of box added https://drive.google.com/drive/folde...2tZZ2szOUtIdmc Last edited by skipjack; January 2nd, 2017 at 07:36 PM. 
January 2nd, 2017, 03:43 AM  #10  
Newbie Joined: Nov 2016 From: St. Louis, Missouri Posts: 24 Thanks: 4 Math Focus: arithmetic, fractions  Quote:
 

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