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Matrices Question 4

  • #1

Homework Statement


If:

A = l 1 -3 l , B = l -1 2 l C = l -12 -11 l
l 2 1 l l 3 1 l l -10 -1 l

Then, find X if AXB=C

Homework Equations





The Attempt at a Solution


I don't know how I would start this problem??
 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
10
I think you would pick 4 variables, say t,u,v,w to represent the 4 elements in matrix X. Perform the multiplication and set the result equal to C. This should give you four ordinary equations, one for each element. Solve them for t,u,v,w.
 
  • #3
When you say: Perform the multiplication and set the result equal to C. Do you mean multiply A&B?
 
  • #4
Delphi51
Homework Helper
3,407
10
"find X if AXB=C" means you multiply A by X, then the result by B.
Set that result equal to C.
 
  • #5
ehild
Homework Helper
15,492
1,874
It might be easier to find the inverse of both A and B and to multiply the matrix equation AXB=C with A-1 from left and B-1 from right to get X. (X=A-1CB-1)

ehild
 
  • #6
559
8
Don't you need the cross product and not multiplication?
 
  • #7
ehild
Homework Helper
15,492
1,874
X is not for "cross product" it is an unknown matrix you need to find.

ehild
 

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