Volume Revolution Bf2A49
1. **Problem:** Find the volume of the solid of revolution formed by revolving the region bounded by $y = x^2$ and $x = y^2$ about the line $y = 1$.
2. **Identify the curves and region:**
- The curves are $y = x^2$ and $x = y^2$.
- Rewrite $x = y^2$ as $y = \sqrt{x}$ (considering positive root since $y \geq 0$).
- The region bounded is between $y = x^2$ and $y = \sqrt{x}$.
3. **Find points of intersection:**
Set $x^2 = \sqrt{x}$.
$$x^2 = x^{1/2} \implies x^{3/2} = 1 \implies x = 1^{2/3} = 1$$
Also, $x=0$ is an intersection.
So, the region is between $x=0$ and $x=1$.
4. **Set up the volume integral using the washer method about $y=1$:**
The distance from $y=1$ to the curve is the radius of the washers.
Outer radius $R = 1 - y_{lower} = 1 - x^2$ (since $y=x^2$ is lower curve)
Inner radius $r = 1 - y_{upper} = 1 - \sqrt{x}$
Volume:
$$V = \pi \int_0^1 \left[(1 - x^2)^2 - (1 - \sqrt{x})^2\right] dx$$
5. **Expand and simplify the integrand:**
$$(1 - x^2)^2 = 1 - 2x^2 + x^4$$
$$(1 - \sqrt{x})^2 = 1 - 2\sqrt{x} + x$$
Subtracting:
$$1 - 2x^2 + x^4 - (1 - 2\sqrt{x} + x) = -2x^2 + x^4 + 2\sqrt{x} - x$$
6. **Integral becomes:**
$$V = \pi \int_0^1 (-2x^2 + x^4 + 2x^{1/2} - x) dx$$
7. **Integrate term-by-term:**
$$\int_0^1 -2x^2 dx = -2 \cdot \frac{x^3}{3} \Big|_0^1 = -\frac{2}{3}$$
$$\int_0^1 x^4 dx = \frac{x^5}{5} \Big|_0^1 = \frac{1}{5}$$
$$\int_0^1 2x^{1/2} dx = 2 \cdot \frac{2}{3} x^{3/2} \Big|_0^1 = \frac{4}{3}$$
$$\int_0^1 -x dx = -\frac{x^2}{2} \Big|_0^1 = -\frac{1}{2}$$
8. **Sum the integrals:**
$$V = \pi \left(-\frac{2}{3} + \frac{1}{5} + \frac{4}{3} - \frac{1}{2}\right) = \pi \left(\frac{-10}{15} + \frac{3}{15} + \frac{20}{15} - \frac{7.5}{15}\right)$$
$$= \pi \left(\frac{-10 + 3 + 20 - 7.5}{15}\right) = \pi \cdot \frac{5.5}{15} = \frac{11\pi}{30}$$
9. **Final answer:**
$$\boxed{\frac{11\pi}{30}}$$
This corresponds to option d.