Inverse of a matrix

I want to solve the following for X2: A = B(X1+X2) where B is a matrix, and A, X1, and X2 are vectors. I can't divide by a matrix. So I believe I take the inverse. Is that right? What is the best way of doing this with very large matrices?

[Matt J]

We would have to know what "very large" means to you.

Answer 1

[Matt J]

%Fake input data
B=rand(100); X1=rand(100,1); X2=rand(100,1);
A=B*(X1+X2);

%Now invert

X2_recovered=B\(A-B*X1);

norm(X2-X2_recovered) %Check discrepancy - should be small

ans = 4.4786e-13