∫Calc Practice

Antiderivatives with initial conditions

Problem 3.431 · hard

Solve \( \displaystyle f''(x) = - x^{3} + \frac{3}{x^{2}} \) with \( \displaystyle f'(1) = 1 \) and \( \displaystyle f(1) = 3 \).
  1. \[ \frac{d}{d x} \left(- \frac{x^{4}}{4} - \frac{3}{x}\right) = - x^{3} + \frac{3}{x^{2}} \]
    An antiderivative of f″; f′ is this plus a constant C₁.✓ Proved
  2. \[ 1 - \left. \frac{\left(-1\right) x^{4}}{4} - \frac{3}{x} \right|_{\substack{ x=1 }} = \frac{17}{4} \]
    f′(1) = 1 fixes C₁.✓ Proved
  3. \[ \frac{d}{d x} \left(- \frac{x^{5}}{20} + \frac{17 x}{4} - 3 \ln{\left(x \right)}\right) = - \frac{x^{4}}{4} + \frac{17}{4} - \frac{3}{x} \]
    Antidifferentiate f′; add a constant C₀.✓ Proved
  4. \[ 3 - \left. \frac{17 x}{4} + \frac{\left(-1\right) x^{5}}{20} - 3 \ln{\left(x \right)} \right|_{\substack{ x=1 }} = - \frac{6}{5} \]
    f(1) = 3 fixes C₀.✓ Proved
  5. \[ \frac{17 x}{4} + \frac{\left(-1\right) x^{5}}{20} - 3 \ln{\left(x \right)} - \frac{6}{5} = - \frac{x^{5}}{20} + \frac{17 x}{4} - 3 \ln{\left(x \right)} - \frac{6}{5} \]
    The solution.✓ Proved
Answer \( f(x) = - \frac{x^{5}}{20} + \frac{17 x}{4} - 3 \ln{\left(x \right)} - \frac{6}{5} \)

✓ 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 1.14.0simplify(lhs - rhs) reduced to 0
2✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
3✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
4✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
5✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
answer, a second way✓ Checked independentlysympy 1.14.0 + mpmath 1.3.0the answer differentiated back to the given derivative, and the initial values checked

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-05
  • gpt-oss:20b: pass 2026-10-05
  • qwen3.6:27b-mlx: pass 2026-10-05
  • gpt-oss:20b: pass 2026-10-05

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 generator:structured/antiderivative_ivp, checked 2026-10-05 with SymPy 1.14.0.