Let $U=\{1,2,3,4,5,6\}, A=\{2,3\}$ and $B=\{3,4,5\}$
Find $A^{\prime}, B^{\prime}, A^{\prime} \cap B^{\prime}, A \cup B$ and hence show that $(A \cup B)^{\prime}=A^{\prime} \cap B^{\prime}$
Clearly $A ^{\prime}=\{1,4,5,6\}, B ^{\prime}=\{1,2,6\} .$ Hence $A ^{\prime} \cap B ^{\prime}=\{1,6\}$
Also $A \cup B = \{ 2,3,4,5\} ,$ so that ${(A \cup B)^\prime } = \{ 1,6\} $
$( A \cup B )^{\prime}=\{1,6\}= A ^{\prime} \cap B ^{\prime}$
It can be shown that the above result is true in general. If $A$ and $B$ are any two subsets of the universal set $U,$ then
${(A \cup B)^\prime } = {A^\prime } \cap {B^\prime }$. Similarly, ${(A \cup B)^\prime } = {A^\prime } \cap {B^\prime }.$ These two results are stated in words as follows:
Draw appropriate Venn diagram for each of the following:
$A^{\prime} \cap B^{\prime}$
Taking the set of natural numbers as the universal set, write down the complements of the following sets:
$\{ x:x$ is a natural number divisible by $ 3 $ and $5\} $
Taking the set of natural numbers as the universal set, write down the complements of the following sets:
$\{ x:x \in N$ and $2x + 1\, > \,10\} $
Fill in the blanks to make each of the following a true statement :
${{\mathop{\rm U}\nolimits} ^\prime } \cap A = \ldots $
Let $U=\{1,2,3,4,5,6,7,8,9\}, A=\{1,2,3,4\}, B=\{2,4,6,8\}$ and $C=\{3,4,5,6\} .$ Find
$(A \cup C)^{\prime}$