Integrate X2Lnx
1. **State the problem:** We need to evaluate the definite integral $$\int_1^4 x^2 \ln x \, dx$$.
2. **Formula and method:** We will use integration by parts, which states:
$$\int u \, dv = uv - \int v \, du$$
Choose:
$$u = \ln x \quad \Rightarrow \quad du = \frac{1}{x} dx$$
$$dv = x^2 dx \quad \Rightarrow \quad v = \frac{x^3}{3}$$
3. **Apply integration by parts:**
$$\int x^2 \ln x \, dx = \frac{x^3}{3} \ln x - \int \frac{x^3}{3} \cdot \frac{1}{x} dx = \frac{x^3}{3} \ln x - \frac{1}{3} \int x^2 dx$$
4. **Integrate remaining integral:**
$$\int x^2 dx = \frac{x^3}{3}$$
5. **Substitute back:**
$$\int x^2 \ln x \, dx = \frac{x^3}{3} \ln x - \frac{1}{3} \cdot \frac{x^3}{3} + C = \frac{x^3}{3} \ln x - \frac{x^3}{9} + C$$
6. **Evaluate definite integral from 1 to 4:**
$$\left[ \frac{x^3}{3} \ln x - \frac{x^3}{9} \right]_1^4 = \left( \frac{4^3}{3} \ln 4 - \frac{4^3}{9} \right) - \left( \frac{1^3}{3} \ln 1 - \frac{1^3}{9} \right)$$
7. **Calculate values:**
$$\ln 1 = 0$$
$$\frac{4^3}{3} = \frac{64}{3}$$
$$\frac{4^3}{9} = \frac{64}{9}$$
So,
$$= \frac{64}{3} \ln 4 - \frac{64}{9} - \left(0 - \frac{1}{9} \right) = \frac{64}{3} \ln 4 - \frac{64}{9} + \frac{1}{9} = \frac{64}{3} \ln 4 - \frac{63}{9} = \frac{64}{3} \ln 4 - 7$$
**Final answer:**
$$\boxed{\frac{64}{3} \ln 4 - 7}$$