Problem 230
Evaluate the integral: I = integral (2x-3)/((x-2)²) dx
Evaluate the integral: $$ I = \int \frac{2x-3}{(x-2)^2}\,dx. $$
Explanation of Method
Writing the numerator in terms of $(x-2)$ splits the integral into a simple $1/(x-2)$ term and a power-rule $1/(x-2)^2$ term.
- Rewrite $2x-3=2(x-2)+1$.
- Split into two elementary integrals.
- Integrate each piece.
Step 1 · Rewrite the numerator
$$ 2x-3 = 2(x-2) + 1. $$
Step 2 · Split the integral
$$ I = \int \frac{2(x-2)}{(x-2)^2}\,dx + \int \frac{1}{(x-2)^2}\,dx = \int \frac{2}{x-2}\,dx + \int \frac{1}{(x-2)^2}\,dx. $$
Step 3 · Integrate each piece
$$ \int \frac{2}{x-2}\,dx = 2\ln|x-2|, \qquad \int \frac{1}{(x-2)^2}\,dx = -\frac{1}{x-2}. $$
Step 4 · Combine
$$ I = 2\ln|x-2| - \frac{1}{x-2} + C. $$
Summary Table
| Piece | Antiderivative |
|---|---|
| $2/(x-2)$ | $2\ln|x-2|$ |
| $1/(x-2)^2$ | $-1/(x-2)$ |
Additional Notes
- The domain excludes $x=2$, the repeated root of the denominator.
- This is the standard technique for a linear-over-repeated-linear-squared integrand: rewriting the numerator in terms of the shifted variable avoids full partial fraction machinery.
- The result can be checked by differentiating $2\ln|x-2|-1/(x-2)$: this gives $\tfrac{2}{x-2}+\tfrac{1}{(x-2)^2}=\tfrac{2(x-2)+1}{(x-2)^2}=\tfrac{2x-3}{(x-2)^2}$, matching the integrand.
Result
The solution to the integral is:
$$
I = 2\ln|x-2| - \frac{1}{x-2} + C.
$$