Question: Solve the problem 9: (a) Sketch the graph of $y = 5 - |x - 2|$. (b) Find the set of values of $x$ for which $y$ is negative. (c) Find the area of the region bounded by the graph and the x-axis.
1. **Problem statement:**
We are given the function $$y = 5 - |x - 2|$$ and need to:
(a) Sketch its graph.
(b) Find the values of $x$ where $y < 0$.
(c) Find the area bounded by the graph and the x-axis.
2. **Understanding the function:**
The function is a vertical shift of the absolute value function $|x - 2|$ reflected and shifted up by 5.
The graph of $y = |x - 2|$ is a V-shape with vertex at $(2,0)$.
So $y = 5 - |x - 2|$ flips it upside down and shifts it up by 5.
3. **Sketching the graph:**
- The vertex is at $x=2$, where $|x-2|=0$, so $y=5$.
- For $x < 2$, $|x-2| = 2 - x$, so $y = 5 - (2 - x) = 3 + x$ (a line with slope 1).
- For $x > 2$, $|x-2| = x - 2$, so $y = 5 - (x - 2) = 7 - x$ (a line with slope -1).
The graph is a "tent" shape with peak at $(2,5)$ and intercepts where $y=0$.
4. **Finding x-intercepts (where $y=0$):**
Set $5 - |x - 2| = 0$:
$$|x - 2| = 5$$
This gives two solutions:
$$x - 2 = 5 \implies x = 7$$
$$x - 2 = -5 \implies x = -3$$
So the graph crosses the x-axis at $x = -3$ and $x = 7$.
5. **Finding where $y$ is negative:**
We want $5 - |x - 2| < 0$:
$$|x - 2| > 5$$
This means $x$ is more than 5 units away from 2:
$$x < -3 \quad \text{or} \quad x > 7$$
6. **Finding the area bounded by the graph and the x-axis:**
The graph is above the x-axis between $x = -3$ and $x = 7$.
Area = integral of $y$ from $-3$ to $7$:
Split integral at $x=2$:
$$\text{Area} = \int_{-3}^{2} (5 - |x - 2|) dx + \int_{2}^{7} (5 - |x - 2|) dx$$
For $x < 2$, $|x - 2| = 2 - x$, so:
$$\int_{-3}^{2} (5 - (2 - x)) dx = \int_{-3}^{2} (3 + x) dx$$
For $x > 2$, $|x - 2| = x - 2$, so:
$$\int_{2}^{7} (5 - (x - 2)) dx = \int_{2}^{7} (7 - x) dx$$
Calculate each:
$$\int_{-3}^{2} (3 + x) dx = \left[3x + \frac{x^2}{2}\right]_{-3}^{2} = \left(3(2) + \frac{2^2}{2}\right) - \left(3(-3) + \frac{(-3)^2}{2}\right) = (6 + 2) - (-9 + 4.5) = 8 - (-4.5) = 12.5$$
$$\int_{2}^{7} (7 - x) dx = \left[7x - \frac{x^2}{2}\right]_{2}^{7} = \left(7(7) - \frac{7^2}{2}\right) - \left(7(2) - \frac{2^2}{2}\right) = (49 - 24.5) - (14 - 2) = 24.5 - 12 = 12.5$$
Total area:
$$12.5 + 12.5 = 25$$
**Final answers:**
(a) The graph is a tent shape with vertex at $(2,5)$ and x-intercepts at $x = -3$ and $x = 7$.
(b) $y$ is negative for $x < -3$ or $x > 7$.
(c) The area bounded by the graph and the x-axis is $25$ square units.