1. **Problem:** Find the values of A, B, and C such that
$$\frac{2x+1}{(x+1)(x+2)^2} = \frac{A}{x+1} + \frac{B}{x+2} + \frac{C}{(x+2)^2}$$
2. **Formula and rules:** For partial fraction decomposition, express the rational function as a sum of simpler fractions with unknown coefficients. Multiply both sides by the denominator to clear fractions:
$$2x+1 = A(x+2)^2 + B(x+1)(x+2) + C(x+1)$$
3. **Expand terms:**
$$A(x^2 + 4x + 4) + B(x^2 + 3x + 2) + C(x+1)$$
4. **Combine like terms:**
$$Ax^2 + 4Ax + 4A + Bx^2 + 3Bx + 2B + Cx + C$$
Group by powers of $x$:
$$ (A + B)x^2 + (4A + 3B + C)x + (4A + 2B + C)$$
5. **Equate coefficients with left side $2x + 1$:**
- Coefficient of $x^2$: $A + B = 0$
- Coefficient of $x$: $4A + 3B + C = 2$
- Constant term: $4A + 2B + C = 1$
6. **Solve system:**
From $A + B = 0$, we get $B = -A$.
Substitute into other equations:
- $4A + 3(-A) + C = 2 \Rightarrow 4A - 3A + C = 2 \Rightarrow A + C = 2$
- $4A + 2(-A) + C = 1 \Rightarrow 4A - 2A + C = 1 \Rightarrow 2A + C = 1$
Subtract second from first:
$A + C - (2A + C) = 2 - 1 \Rightarrow -A = 1 \Rightarrow A = -1$
Then $B = -A = 1$.
From $A + C = 2$, $-1 + C = 2 \Rightarrow C = 3$.
7. **Answer:** $A = -1$, $B = 1$, $C = 3$ which corresponds to option C.
**Final answer:** C) -1, 1, 3
Partial Fractions 9Fa6Ef
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