Question: Write a function $g$ whose graph represents the indicated transformations of the graph of $f$
$f(x) = |x|$ : reflection in the x-axis and a vertical stretch by a factor of 4
g(x) = ___
1. **State the problem:** We start with the function $f(x) = |x|$ and want to find a function $g(x)$ that represents a reflection of $f(x)$ in the x-axis and a vertical stretch by a factor of 4.
2. **Recall the transformations:**
- Reflection in the x-axis changes $f(x)$ to $-f(x)$.
- Vertical stretch by a factor of 4 changes $f(x)$ to $4f(x)$.
3. **Apply the transformations step-by-step:**
- Reflect $f(x)$ in the x-axis: $-f(x) = -|x|$.
- Stretch vertically by 4: $4 \times (-|x|) = -4|x|$.
4. **Write the final function:**
$$
g(x) = -4|x|
$$
5. **Explanation:**
The original graph $f(x) = |x|$ is a V-shaped graph opening upwards. Reflecting it in the x-axis flips it upside down, so it opens downwards. Then stretching it vertically by 4 makes it 4 times taller (or deeper) than the original. The resulting graph $g(x) = -4|x|$ is a V-shaped graph opening downwards, centered at the origin, and vertically stretched by 4 times.