Domain Range Composition
1. **Find the domain and range of the function** $h(x) = \sqrt{x^2 - 4}$.
Step 1: The expression under the square root, called the radicand, must be non-negative for $h(x)$ to be real.
$$x^2 - 4 \geq 0$$
Step 2: Solve the inequality.
$$x^2 \geq 4$$
This means:
$$x \leq -2 \quad \text{or} \quad x \geq 2$$
So, the domain of $h$ is:
$$(-\infty, -2] \cup [2, \infty)$$
Step 3: Find the range.
Since $h(x) = \sqrt{x^2 - 4} \geq 0$ for all $x$ in the domain.
Step 4: Find minimum value.
At $x=\pm 2$,
$$h(2) = \sqrt{2^2 - 4} = \sqrt{0} = 0$$
As $|x|$ increases, $x^2 - 4$ increases, so $h(x)$ becomes larger without bound.
Hence range is:
$$[0, \infty)$$
2. **Determine $(g \circ h)(x)$ given:**
$$g(x) = x^2 + 2, \quad h(x) = \sqrt{x^2 - 4}$$
Step 1: Compose the functions:
$$(g \circ h)(x) = g(h(x)) = \left(\sqrt{x^2 - 4}\right)^2 + 2$$
Step 2: Simplify:
$$ (g \circ h)(x) = x^2 - 4 + 2 = x^2 - 2$$
Step 3: Remember that the domain of $(g \circ h)(x)$ comes from the domain of $h(x)$ since $h(x)$ must be defined.
So, domain is:
$$(-\infty, -2] \cup [2, \infty)$$
**Final answers:**
- Domain of $h(x)$: $(-\infty, -2] \cup [2, \infty)$
- Range of $h(x)$: $[0, \infty)$
- $(g \circ h)(x) = x^2 - 2$ with domain $(-\infty, -2] \cup [2, \infty)$