method (1)
LHS=A x-nor (BC)=ABC+(A)'(BC)'=ABC+(A)'(B'+C')=ABC+A'B'+A'C'
RHS=(AB+A'B')(AC+A'C')=ABC+A'B'C'
SO, LHS!=RHS
method(2)
A |
B |
C |
Ax-nor(BC) |
(A xnor B)(A xnor C) |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
so from this truth table also LHS != RHS