1. **State the problem:** We are given two functions $f(x) = x^2 - 7x + 12$ and $g(x) = \frac{3x}{4} + \frac{21}{4}$.
We want to write the integral with respect to $y$ to find the area of the region bounded above by $f(x)$ and $g(x)$ and bounded below by the $x$-axis.
2. **Understand the problem:** The region is bounded below by the $x$-axis ($y=0$), and above by the curves $f(x)$ and $g(x)$. Since we integrate with respect to $y$, we need to express $x$ as a function of $y$ for both curves.
3. **Rewrite the functions in terms of $y$:**
- For the line $g(x)$:
$$y = \frac{3x}{4} + \frac{21}{4} \implies y - \frac{21}{4} = \frac{3x}{4} \implies x = \frac{4}{3}\left(y - \frac{21}{4}\right) = \frac{4y}{3} - 7$$
- For the parabola $f(x)$:
$$y = x^2 - 7x + 12$$
Rewrite as:
$$x^2 - 7x + (12 - y) = 0$$
4. **Solve for $x$ in terms of $y$ using the quadratic formula:**
$$x = \frac{7 \pm \sqrt{(-7)^2 - 4 \cdot 1 \cdot (12 - y)}}{2} = \frac{7 \pm \sqrt{49 - 48 + 4y}}{2} = \frac{7 \pm \sqrt{1 + 4y}}{2}$$
5. **Determine the relevant branch of the parabola:**
Since the parabola opens upward and the region is between $x=2$ and $x=6$, the left branch corresponds to the minus sign:
$$x = \frac{7 - \sqrt{1 + 4y}}{2}$$
6. **Set the limits for $y$:**
The region is bounded below by $y=0$ (the $x$-axis) and above by the intersection of $f(x)$ and $g(x)$.
7. **Find the intersection points of $f(x)$ and $g(x)$ to find the upper limit for $y$:**
Set $f(x) = g(x)$:
$$x^2 - 7x + 12 = \frac{3x}{4} + \frac{21}{4}$$
Multiply both sides by 4:
$$4x^2 - 28x + 48 = 3x + 21$$
Rearrange:
$$4x^2 - 31x + 27 = 0$$
8. **Solve quadratic for $x$:**
$$x = \frac{31 \pm \sqrt{31^2 - 4 \cdot 4 \cdot 27}}{2 \cdot 4} = \frac{31 \pm \sqrt{961}}{8} = \frac{31 \pm 31}{8}$$
So $x= \frac{31 - 31}{8} = 0$ or $x= \frac{31 + 31}{8} = \frac{62}{8} = 7.75$.
9. **Find corresponding $y$ values at these $x$ values:**
For $x=0$:
$$y = f(0) = 0^2 - 7 \cdot 0 + 12 = 12$$
For $x=7.75$:
$$y = f(7.75) = (7.75)^2 - 7 \cdot 7.75 + 12 = 60.0625 - 54.25 + 12 = 17.8125$$
10. **Check the region's $y$ bounds:**
The graph description says the region is between approximately $y=4$ and $y=6$, so we consider the intersection points relevant to that range.
11. **Write the integral with respect to $y$:**
The horizontal slices run from the parabola (left) to the line (right), so the length of each slice is:
$$x_{right} - x_{left} = \left(\frac{4y}{3} - 7\right) - \frac{7 - \sqrt{1 + 4y}}{2}$$
12. **Integral for the area:**
$$\text{Area} = \int_{y=0}^{y=6} \left[ \left(\frac{4y}{3} - 7\right) - \frac{7 - \sqrt{1 + 4y}}{2} \right] dy$$
**Final answer:**
$$\boxed{\int_0^6 \left( \frac{4y}{3} - 7 - \frac{7}{2} + \frac{\sqrt{1 + 4y}}{2} \right) dy}$$
or equivalently
$$\int_0^6 \left( \frac{4y}{3} - \frac{21}{2} + \frac{\sqrt{1 + 4y}}{2} \right) dy$$
Area By Y 7Ba553
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