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 $A = B$. (Hint: Use $A = A \cap (A \cup X)$,$B = B \cap (B \cup X)$ and the Distributive law.)

Vedclass pdf generator app on play store
Vedclass iOS app on app store
Given that $A \cap X = \phi$,$B \cap X = \phi$,and $A \cup X = B \cup X$ for some set $X$.
To show: $A = B$.
We know that $A = A \cap (A \cup X)$.
Substituting $A \cup X = B \cup X$,we get:
$A = A \cap (B \cup X)$.
Using the Distributive law,$A = (A \cap B) \cup (A \cap X)$.
Since $A \cap X = \phi$,we have $A = (A \cap B) \cup \phi = A \cap B$ ... $(1)$.
Similarly,$B = B \cap (B \cup X)$.
Substituting $B \cup X = A \cup X$,we get:
$B = B \cap (A \cup X)$.
Using the Distributive law,$B = (B \cap A) \cup (B \cap X)$.
Since $B \cap X = \phi$,we have $B = (B \cap A) \cup \phi = B \cap A = A \cap B$ ... $(2)$.
From $(1)$ and $(2)$,we conclude that $A = B$.

Explore More

Similar Questions

If $A = \{1, 2, 3, 4, 5, 6\}$, then which of the following is not true?

If $A = \{x \in \mathbb{R} : x^2 + 5|x| + 6 = 0\}$,then $n(A) = $

Let $a, b, c$ be real numbers. $A$ set formed with $a, b, c$ whose order of occurrence is preassigned is called:

Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$5 \dots A$

If ${N_a} = \{an : n \in N\}$,then ${N_3} \cap {N_4} = $

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo