Given the matrices
and 
Verify that (A + B) + C = A + (B + C).
L.H.S (A+B)+C
= (A+B)=
+
=
=
= (A+B)+C = 
=
= (A+B)+C
R.H.S A+(B+C)
= (B+C)
+
= 
= 
= A+(B+C)
+
Hence, L.H.S=R.H.S
6
Given the matrices
and
Verify that (A + B) + C = A + (B + C).
L.H.S (A+B)+C
= (A+B)=+
=
=
= (A+B)+C =
=
= (A+B)+C
R.H.S A+(B+C)
= (B+C)+
=
=
= A+(B+C)+
Hence, L.H.S=R.H.S