The image shows a double integral in polar coordinates that is used to compute the volume of a solid. The integral provided is:

$\int_{A}^{B} \int_{C}^{D} r \sqrt{18 - r^2 - r} \, dr \, d\theta$

where the limits of integration are:

• $A = 0$
• $B = 2\pi$
• $C = 0$
• $D = 3$

This suggests that the problem involves finding the volume of a 3D solid using cylindrical coordinates (based on the $r$ term and the angular component $d\theta$).

Steps to Solve:

1. Set up the integrals: The outer integral is with respect to $\theta$ from $0$ to $2\pi$, and the inner integral is with respect to $r$, from $0$ to $3$.
2. Focus on the inner integral: The function to integrate is $r \sqrt{18 - r^2 - r}$ with respect to $r$.
3. Outer integral: Once the inner integral is evaluated, we integrate with respect to $\theta$, which would likely result in multiplying by $2\pi$, the full angle in radians.

Would you like me to go ahead and evaluate this integral for the volume, and provide details on each step?

If so, here are some questions you might consider:

1. Would you like a more detailed explanation of cylindrical coordinates?
2. Should I explain how the limits of integration are set?
3. Do you need more background on how the volume integral formula works in this case?
4. Are you interested in simplifications of the integral before solving it?
5. Do you have a specific question about the role of the function $\sqrt{18 - r^2 - r}$?

Tip: For problems involving volume in polar or cylindrical coordinates, always check if the limits correspond to common shapes like cylinders or spheres to simplify integration.