# Matrices Question 4

## 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

## The Attempt at a Solution

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

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Delphi51
Homework Helper
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.

When you say: Perform the multiplication and set the result equal to C. Do you mean multiply A&B?

Delphi51
Homework Helper
"find X if AXB=C" means you multiply A by X, then the result by B.
Set that result equal to C.

ehild
Homework Helper
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

Don't you need the cross product and not multiplication?

ehild
Homework Helper
X is not for "cross product" it is an unknown matrix you need to find.

ehild