1. **State the problem:** We want to evaluate the integral $$\int \frac{7x^3 - 8x + 5}{x^3 - x^2} \, dx$$ by first performing long division, then expressing the proper fraction as partial fractions, and finally integrating.
2. **Perform long division:** Divide the numerator by the denominator.
Divide $$7x^3$$ by $$x^3$$ to get $$7$$.
Multiply $$7$$ by the denominator $$x^3 - x^2$$ to get $$7x^3 - 7x^2$$.
Subtract this from the numerator:
$$\begin{aligned}
(7x^3 - 8x + 5) - (7x^3 - 7x^2) &= 7x^3 - 8x + 5 - 7x^3 + 7x^2 \\
&= 7x^2 - 8x + 5
\end{aligned}$$
So the division gives:
$$\frac{7x^3 - 8x + 5}{x^3 - x^2} = 7 + \frac{7x^2 - 8x + 5}{x^3 - x^2}$$
3. **Factor the denominator of the proper fraction:**
$$x^3 - x^2 = x^2(x - 1)$$
4. **Set up partial fractions:**
$$\frac{7x^2 - 8x + 5}{x^2(x - 1)} = \frac{A}{x} + \frac{B}{x^2} + \frac{C}{x - 1}$$
Multiply both sides by $$x^2(x - 1)$$:
$$7x^2 - 8x + 5 = A x (x - 1) + B (x - 1) + C x^2$$
5. **Expand the right side:**
$$A x^2 - A x + B x - B + C x^2 = (A + C) x^2 + (B - A) x - B$$
6. **Equate coefficients:**
For $$x^2$$: $$7 = A + C$$
For $$x$$: $$-8 = B - A$$
For constant term: $$5 = -B$$
7. **Solve the system:**
From constant term: $$B = -5$$
From $$x$$ term: $$-8 = -5 - A \Rightarrow A = -5 + 8 = 3$$
From $$x^2$$ term: $$7 = 3 + C \Rightarrow C = 4$$
8. **Rewrite the integrand:**
$$\frac{7x^3 - 8x + 5}{x^3 - x^2} = 7 + \frac{3}{x} - \frac{5}{x^2} + \frac{4}{x - 1}$$
9. **Integrate term-by-term:**
$$\int \left(7 + \frac{3}{x} - \frac{5}{x^2} + \frac{4}{x - 1}\right) dx = \int 7 \, dx + \int \frac{3}{x} \, dx - \int \frac{5}{x^2} \, dx + \int \frac{4}{x - 1} \, dx$$
Calculate each integral:
$$7x + 3 \ln|x| + 5 \frac{1}{x} + 4 \ln|x - 1| + C$$
(Note: Integral of $$-5/x^2 = -5 \int x^{-2} dx = -5 (-x^{-1}) = 5/x$$)
**Final answer:**
$$\int \frac{7x^3 - 8x + 5}{x^3 - x^2} \, dx = 7x + 3 \ln|x| + \frac{5}{x} + 4 \ln|x - 1| + C$$
Integral Partial Fractions E414B5
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