A=[2,1;-1,-1]

A =

     2     1
    -1    -1

B=[1,-1;2,-1]

B =

     1    -1
     2    -1

a=11;
b=-4;
c=-9;
d=6;
X=[a,b;c,d]

X =

    11    -4
    -9     6

LStran=A*X-X*B

LStran =

    10     5
    -5    -5

DStran=5*A

DStran =

    10     5
    -5    -5

diary off