Q. 11 Let A and B be sets. If A X B X and A X B X for some set X, show that A B.
Given, A X B X and A X B X
To prove: A = B
A = A (AX) (A X B X)
= A (BX)
= (AB) (AX)
= (AB) (A X )
= (AB)
B = B (BX) (A X B X)
= B (AX)
= (BA) (BX)
= (BA) (B X )
= (BA)
We know that (AB) = (BA) = A = B
Hence, A = B