If A = {2, 3, 5} and B = {5, 7}, find:
(i) $A \times B$
(ii) $\mathbf{B} \times \mathbf{A}$
(iii) $\mathbf{A} \times \mathbf{A}$
(iv) $\mathrm{B} \times \mathrm{B}$
(i) Given: A = {2, 3, 5} and B = {5, 7}
To find: A × B
By the definition of the Cartesian product,
Given two non – empty sets P and Q. The Cartesian product P × Q is the set of all ordered pairs of elements from P and Q, .i.e.
$P \times Q=\{(p, q): p \in P, q \in Q\}$
Here, $A=\{2,3,5\}$ and $B=\{5,7\}$. So,
$A \times B=(2,3,5) \times(5,7)$
$=\{(2,5),(3,5),(5,5),(2,7),(3,7),(5,7)\}$
(ii) Given: $A=\{2,3,5\}$ and $B=\{5,7\}$
To find: B × A
By the definition of the Cartesian product,
Given two non – empty sets P and Q. The Cartesian product P × Q is the set of all ordered pairs of elements from P and Q, .i.e.
$P \times Q=\{(p, q): p \in P, q \in Q\}$
Here, $A=\{2,3,5\}$ and $B=\{5,7\}$. So,
$B \times A=(5,7) \times(2,3,5)$
$=\{(5,2),(5,3),(5,5),(7,2),(7,3),(7,5)\}$
(iii) Given: $A=\{2,3,5\}$ and $B=\{2,3,5\}$
To find: A × A
By the definition of the Cartesian product,
Given two non – empty sets P and Q. The Cartesian product P × Q is the set of all ordered pairs of elements from P and Q, .i.e.
$P \times Q=\{(p, q): p \in P, q \in Q\}$
Here, $A=\{2,3,5\}$ and $A=\{2,3,5\} .$ So,
$A \times A=(2,3,5) \times(2,3,5)$ $=\{(2,2),(2,3),(2,5),(3,2),(3,3),(3,5),(5,2),(5,3),(5,5)\}$
(iv) Given: B = {5, 7}
To find: B × B
By the definition of the Cartesian product,
Given two non – empty sets P and Q. The Cartesian product P × Q is the set of all ordered pairs of elements from P and Q, .i.e.
$P \times Q=\{(p, q): p \in P, q \in Q\}$
Here, $B=\{5,7\}$ and $B=\{5,7\} .$ So,
$B \times B=(5,7) \times(5,7)$
$=\{(5,5),(5,7),(7,5),(7,7)\}$