1. **State the problem:** We want to express the integrand $$\frac{16x^2}{(x-12)(x+4)^2}$$ as a sum of partial fractions and then evaluate the integral $$\int \frac{16x^2}{(x-12)(x+4)^2} \, dx$$.
2. **Set up the partial fraction decomposition:** Since the denominator has a linear factor $(x-12)$ and a repeated linear factor $(x+4)^2$, the decomposition form is:
$$\frac{16x^2}{(x-12)(x+4)^2} = \frac{A}{x-12} + \frac{B}{x+4} + \frac{C}{(x+4)^2}$$
3. **Multiply both sides by the denominator to clear fractions:**
$$16x^2 = A(x+4)^2 + B(x-12)(x+4) + C(x-12)$$
4. **Expand each term:**
- $(x+4)^2 = x^2 + 8x + 16$
- $(x-12)(x+4) = x^2 - 8x - 48$
So,
$$16x^2 = A(x^2 + 8x + 16) + B(x^2 - 8x - 48) + C(x - 12)$$
5. **Expand and group terms:**
$$16x^2 = (A + B) x^2 + (8A - 8B + C) x + (16A - 48B - 12C)$$
6. **Equate coefficients of powers of $x$ on both sides:**
- Coefficient of $x^2$: $16 = A + B$
- Coefficient of $x$: $0 = 8A - 8B + C$
- Constant term: $0 = 16A - 48B - 12C$
7. **Solve the system:**
From $16 = A + B$, we get $B = 16 - A$.
Substitute into the $x$ coefficient equation:
$$0 = 8A - 8(16 - A) + C = 8A - 128 + 8A + C = 16A - 128 + C$$
So,
$$C = 128 - 16A$$
Substitute $B$ and $C$ into the constant term equation:
$$0 = 16A - 48(16 - A) - 12(128 - 16A)$$
$$0 = 16A - 768 + 48A - 1536 + 192A$$
$$0 = (16A + 48A + 192A) - (768 + 1536)$$
$$0 = 256A - 2304$$
Solve for $A$:
$$256A = 2304 \implies A = \frac{2304}{256} = 9$$
Then,
$$B = 16 - 9 = 7$$
$$C = 128 - 16 \times 9 = 128 - 144 = -16$$
8. **Write the partial fraction decomposition:**
$$\frac{16x^2}{(x-12)(x+4)^2} = \frac{9}{x-12} + \frac{7}{x+4} - \frac{16}{(x+4)^2}$$
9. **Integrate term-by-term:**
$$\int \frac{16x^2}{(x-12)(x+4)^2} \, dx = \int \frac{9}{x-12} \, dx + \int \frac{7}{x+4} \, dx - \int \frac{16}{(x+4)^2} \, dx$$
10. **Integrate each term:**
- $$\int \frac{9}{x-12} \, dx = 9 \ln|x-12| + C_1$$
- $$\int \frac{7}{x+4} \, dx = 7 \ln|x+4| + C_2$$
- $$\int \frac{16}{(x+4)^2} \, dx = 16 \int (x+4)^{-2} \, dx = 16 \left(-\frac{1}{x+4}\right) + C_3 = -\frac{16}{x+4} + C_3$$
11. **Combine the results:**
$$\int \frac{16x^2}{(x-12)(x+4)^2} \, dx = 9 \ln|x-12| + 7 \ln|x+4| - \frac{16}{x+4} + C$$
**Final answer:**
$$\boxed{9 \ln|x-12| + 7 \ln|x+4| - \frac{16}{x+4} + C}$$
Partial Fractions Integral E566Ff
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.