Relations Functions 7Ffe5D
1. **Problem Statement:**
Given sets $A = B = \{1,2,3,4\}$ and relations:
$$R_1 = \{(x,y) \mid x \in A, y \in B, x = y^2 + 1\}$$
$$R_2 = \{(x,y) \mid x \in A, y \in B, x \text{ is even and } y \text{ is odd}\}$$
Find:
(i) The ordered pairs for $R_1$ and $R_2$.
(ii) The domain and range of $R_1$ and $R_2$.
(iii) Whether $R_1$ and $R_2$ represent functions.
2. **Step (i): Write relations as ordered pairs.**
- For $R_1$, find all $(x,y)$ with $x = y^2 + 1$ and $x,y \in \{1,2,3,4\}$.
Check each $y$:
- $y=1$: $x = 1^2 + 1 = 2$ (in $A$)
- $y=2$: $x = 2^2 + 1 = 5$ (not in $A$)
- $y=3$: $x = 3^2 + 1 = 10$ (not in $A$)
- $y=4$: $x = 4^2 + 1 = 17$ (not in $A$)
So $R_1 = \{(2,1)\}$.
- For $R_2$, $x$ is even and $y$ is odd, both in $\{1,2,3,4\}$.
Even $x$: $2,4$
Odd $y$: $1,3$
So $R_2 = \{(2,1),(2,3),(4,1),(4,3)\}$.
3. **Step (ii): Domain and range.**
- $R_1$ domain: all $x$ values in pairs $= \{2\}$
- $R_1$ range: all $y$ values in pairs $= \{1\}$
- $R_2$ domain: $\{2,4\}$
- $R_2$ range: $\{1,3\}$
4. **Step (iii): Check if relations are functions.**
A relation is a function if each element in the domain maps to exactly one element in the range.
- $R_1$: Domain $\{2\}$ maps to $1$ only, so $R_1$ is a function.
- $R_2$: Domain $2$ maps to $1$ and $3$ (two outputs), so $R_2$ is not a function.
**Final answers:**
(i) $R_1 = \{(2,1)\}$, $R_2 = \{(2,1),(2,3),(4,1),(4,3)\}$
(ii) $\text{Domain}(R_1) = \{2\}$, $\text{Range}(R_1) = \{1\}$
$\text{Domain}(R_2) = \{2,4\}$, $\text{Range}(R_2) = \{1,3\}$
(iii) $R_1$ is a function; $R_2$ is not a function.