Let $A$ and $B$ be sets. If $A \cap X=B \cap X=\phi$ and $A \cup X=B \cup X$ for some set $X ,$ show that $A = B$

( Hints $A = A \cap (A \cup X),B = B \cap (B \cup X)$ and use Distributive law )

Vedclass pdf generator app on play store
Vedclass iOS app on app store

Let $A$ and $B$ be two sets such that $A \cap X=B \cap x=f$ and $A \cup X=B \cup X$ for some

To show: $A=B$

It can be seen that

$A=A \cap(A \cup X)=A \cap(B \cup X)[A \cup X=B \cup X]$

$=(A \cap B) \cup(A \cap X)$               [Distributive law]

$=(A \cap B) \cup \varnothing[A \cap X=\varnothing]$

$=A \cap B$          .........$(1)$

Now, $B=B \cap(B \cup X)$

$=B \cap(A \cup X)[A \cup X=B \cup X]$

$=(B \cap A) \cup(B \cap X)$            [Distributive law]

$=(B \cap A) \cup \varnothing[B \cap X=\varnothing]$

$=B \cap A$

$=A \cap B$        ...........$(2)$

Hence, from $(1)$ and $(2),$ we obtain $A = B$

Similar Questions

Let $A, B$ and $C$ be sets such that $\phi  \ne A \cap B \subseteq C$. Then which of the following statements is not true ?

  • [JEE MAIN 2019]

If $A, B, C$ be three sets such that $A \cup B = A \cup C$ and $A \cap B = A \cap C$, then

If $A = \{ x:x$ is a natural number $\} ,B = \{ x:x$ is an even natural number $\} $ $C = \{ x:x$ is an odd natural number $\} $ and $D = \{ x:x$ is a prime number $\} ,$ find

$A \cap B$

Let $A=\{a, b\}, B=\{a, b, c\} .$ Is $A \subset B \,?$ What is $A \cup B \,?$

If the sets $A$ and $B$ are defined as $A = \{ (x,\,y):y = {1 \over x},\,0 \ne x \in R\} $ $B = \{ (x,y):y =  - x,x \in R\} $, then