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Integral of \( \displaystyle \frac{\left(x - 1\right)^{2} + 1}{\left(x - 2\right) \left(x - 1\right)} \)

Problem 4.227 · medium

Find \( \displaystyle \int \frac{\left(x - 1\right)^{2} + 1}{\left(x - 2\right) \left(x - 1\right)} \, dx \). (Omit the constant of integration.)
  1. \[ \int \frac{\left(x - 1\right)^{2} + 1}{\left(x - 2\right) \left(x - 1\right)}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \frac{x^{2} - 2 x + 2}{\left(x - 2\right) \left(x - 1\right)}\, dx \]
    algebraExpand the numerator.✓ Proved
  3. \[ = \int \frac{x + \left(x - 2\right) \left(x - 1\right)}{\left(x - 2\right) \left(x - 1\right)}\, dx \]
    algebraRewrite the numerator to facilitate division.✓ Proved
  4. \[ = \int \left(\frac{x}{\left(x - 2\right) \left(x - 1\right)} + 1\right)\, dx \]
    long-division algebraPerform polynomial division. Split the numerator of the remainder term.✓ Proved
  5. \[ = \int \left(1 + \frac{1}{x - 1} + \frac{2}{\left(x - 2\right) \left(x - 1\right)}\right)\, dx \]
    algebraSimplify the fraction by canceling (x - 2).✓ Proved
  6. \[ = \int \left(1 - \frac{1}{x - 1} + \frac{2}{x - 2}\right)\, dx \]
    partial-fractions simplifyApply partial fraction decomposition to the last term. Combine like terms.✓ Proved
  7. \[ = \int 1\, dx + \int \frac{2}{x - 2}\, dx - \int \frac{1}{x - 1}\, dx \]
    linearityDistribute the integral across the terms.✓ Proved
  8. \[ = x + 2 \ln{\left(x - 2 \right)} - \ln{\left(x - 1 \right)} \]
    antiderivativeEvaluate the integrals.✓ Proved
Answer \( x + 2 \ln{\left(x - 2 \right)} - \ln{\left(x - 1 \right)} + C \)

✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation.

The full receipt
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 1 = 0
undefined where x - 2 = 0
log is undefined for non-positive arguments
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
log is undefined for non-positive arguments
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated the stated antiderivative back to the integrand

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass — The solution correctly applies algebraic manipulation, partial fraction decomposition, and linearity of integration. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-03 — The solution correctly applies algebraic manipulation, partial fraction decomposition, and linearity of integration. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-10-03
  • qwen3.6:27b-mlx: pass 2026-10-03 — The solution correctly applies algebraic manipulation, partial fraction decomposition, and linearity of integration. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-10-03

Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence, not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by gemma4:26b, checked 2026-10-03 with SymPy 1.14.0.