Let 
and a = 4, b = –2.
Show that:
A + (B + C) = (A + B) + C
Given A = 
B = 
and C = 
LHS = A + (B + C) = 
⇒ LHS = 
⇒ LHS = 
RHS = (A + B) + C = 
⇒ RHS = 
⇒ RHS = 
Clearly LHS = RHS = 
Hence,
A + (B + C) = (A + B) + C …proved
32
Let and a = 4, b = –2.
Show that:
A + (B + C) = (A + B) + C
Given A = B = and C =
LHS = A + (B + C) =
⇒ LHS =
⇒ LHS =
RHS = (A + B) + C =
⇒ RHS =
⇒ RHS =
Clearly LHS = RHS =
Hence,
A + (B + C) = (A + B) + C …proved