Let’s assume,
A={ 1,2 } B={ 1,3 } C={ 1,4 }
A∩B={ 1,2 }∩{ 1,3 } ={ 1 } (1)
A∩C={ 1,2 }∩{ 1,4 } ={ 1 } (2)
From equation (1) and (2),
A∩B=A∩C
Hence,
But,
B ≠ C
Because 3∈B , 3∉C
Thus, it is proved that A∩B = A∩C need not imply B = C.
Show that A intersection B is equal to A intersection C need not imply B=C
For three sets A, B and C, show that
(i) A∩B=A∩C need not imply B = C.
(ii) A⊂B⇒C−B⊂C−A