Integral X2 Sinx 3A8834
1. **State the problem:** We need to find the integral $$\int x^2 \sin x \, dx$$.
2. **Formula and method:** We will use integration by parts, which states:
$$\int u \, dv = uv - \int v \, du$$
3. **Choose parts:** Let
$$u = x^2 \implies du = 2x \, dx$$
$$dv = \sin x \, dx \implies v = -\cos x$$
4. **Apply integration by parts:**
$$\int x^2 \sin x \, dx = -x^2 \cos x - \int -\cos x (2x) \, dx = -x^2 \cos x + 2 \int x \cos x \, dx$$
5. **Integrate $$\int x \cos x \, dx$$ by parts again:**
Let
$$u = x \implies du = dx$$
$$dv = \cos x \, dx \implies v = \sin x$$
6. **Apply integration by parts again:**
$$\int x \cos x \, dx = x \sin x - \int \sin x \, dx = x \sin x + \cos x + C$$
7. **Substitute back:**
$$\int x^2 \sin x \, dx = -x^2 \cos x + 2(x \sin x + \cos x) + C = -x^2 \cos x + 2x \sin x + 2 \cos x + C$$
**Final answer:**
$$\int x^2 \sin x \, dx = -x^2 \cos x + 2x \sin x + 2 \cos x + C$$