1. **State the problem:**
We have two functions $f$ and $g$ with given domains and ranges.
We want to find the domain and range of the composition $g \circ f$, which means $g(f(x))$.
2. **Recall the definition of composition:**
The domain of $g \circ f$ consists of all $x$ in the domain of $f$ such that $f(x)$ is in the domain of $g$.
The range of $g \circ f$ is the set of all values $g(f(x))$ for $x$ in the domain of $g \circ f$.
3. **Given data:**
- Domain of $f = \{1, 2, 5, 7\}$
- Range of $f = \{0, 6, 8\}$ with mappings:
$1 \to 0$, $2 \to 6$, $5 \to 8$, $7 \to 0$
- Domain of $g = \{0, 1, 2, 3, 6, 9\}$
- Range of $g = \{0, 4\}$ with mappings:
$0 \to 4$, $1 \to 0$, $2 \to 0$, $3 \to 0$, $6 \to 4$, $9 \to 0$
4. **Find domain of $g \circ f$:**
We check which $x$ in domain of $f$ have $f(x)$ in domain of $g$.
- $f(1) = 0$, and $0 \in$ domain of $g$ (yes)
- $f(2) = 6$, and $6 \in$ domain of $g$ (yes)
- $f(5) = 8$, but $8 \notin$ domain of $g$ (no)
- $f(7) = 0$, and $0 \in$ domain of $g$ (yes)
So domain of $g \circ f = \{1, 2, 7\}$.
5. **Find range of $g \circ f$:**
Calculate $g(f(x))$ for $x$ in domain of $g \circ f$:
- $g(f(1)) = g(0) = 4$
- $g(f(2)) = g(6) = 4$
- $g(f(7)) = g(0) = 4$
Range of $g \circ f = \{4\}$.
**Final answers:**
(a) Domain of $g \circ f = \{1, 2, 7\}$
(b) Range of $g \circ f = \{4\}$
Composition Domain Range E04718
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