1. Problem: Evaluate and find the domain of the composite functions given:
a. $f(x) = \sqrt{x - 2}$ and $g(x) = 5x$, find $(f \circ g)(x)$ and its domain.
b. $f(x) = \sqrt{x - 2}$ and $g(x) = 5x$, find $(g \circ f)(x)$ and its domain.
2. Formula and rules:
- Composite function $(f \circ g)(x) = f(g(x))$ means substitute $g(x)$ into $f$.
- Domain of composite function is all $x$ in domain of $g$ such that $g(x)$ is in domain of $f$.
- For $f(x) = \sqrt{x - 2}$, domain is $x - 2 \geq 0 \Rightarrow x \geq 2$.
3. Evaluate $(f \circ g)(x)$:
$$ (f \circ g)(x) = f(g(x)) = f(5x) = \sqrt{5x - 2} $$
Domain condition: $5x - 2 \geq 2$ because inside the square root must be $\geq 0$.
Simplify domain:
$$ 5x - 2 \geq 2 $$
$$ 5x \geq 4 $$
$$ x \geq \frac{4}{5} $$
So domain of $(f \circ g)(x)$ is $[\frac{4}{5}, \infty)$.
4. Evaluate $(g \circ f)(x)$:
$$ (g \circ f)(x) = g(f(x)) = g(\sqrt{x - 2}) = 5 \cdot \sqrt{x - 2} $$
Domain condition: $x - 2 \geq 0 \Rightarrow x \geq 2$.
So domain of $(g \circ f)(x)$ is $[2, \infty)$.
5. Problem: Use $f(x) = x - 5$ and $g(x) = \frac{2}{x}$ to find $(f \circ g)(x)$ and its domain.
6. Evaluate $(f \circ g)(x)$:
$$ (f \circ g)(x) = f(g(x)) = f\left(\frac{2}{x}\right) = \frac{2}{x} - 5 $$
7. Domain considerations:
- $g(x) = \frac{2}{x}$ is defined for $x \neq 0$.
- $f(x) = x - 5$ is defined for all real numbers.
So domain of $(f \circ g)(x)$ is all real $x$ except $x \neq 0$.
Final answers:
- $(f \circ g)(x) = \sqrt{5x - 2}$ with domain $x \geq \frac{4}{5}$.
- $(g \circ f)(x) = 5 \sqrt{x - 2}$ with domain $x \geq 2$.
- $(f \circ g)(x) = \frac{2}{x} - 5$ with domain $x \neq 0$.
Function Composition 501634
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.