∫Calc Practice

Antiderivatives with initial conditions

Problem 3.477 · hard

Solve \( \displaystyle f''(x) = \sqrt{x} + 4 x^{3} \) with \( \displaystyle f'(1) = -2 \) and \( \displaystyle f(1) = -4 \).
  1. \[ \frac{d}{d x} \left(\frac{2 x^{\frac{3}{2}}}{3} + x^{4}\right) = \sqrt{x} + 4 x^{3} \]
    An antiderivative of f″; f′ is this plus a constant C₁.✓ Proved
  2. \[ - \left. x^{4} + \frac{2 x^{\frac{3}{2}}}{3} \right|_{\substack{ x=1 }} - 2 = - \frac{11}{3} \]
    f′(1) = -2 fixes C₁.✓ Proved
  3. \[ \frac{d}{d x} \left(\frac{4 x^{\frac{5}{2}}}{15} + \frac{x^{5}}{5} - \frac{11 x}{3}\right) = \frac{2 x^{\frac{3}{2}}}{3} + x^{4} - \frac{11}{3} \]
    Antidifferentiate f′; add a constant C₀.✓ Proved
  4. \[ - \left. \frac{x^{5}}{5} - \frac{11 x}{3} + \frac{4 x^{\frac{5}{2}}}{15} \right|_{\substack{ x=1 }} - 4 = - \frac{4}{5} \]
    f(1) = -4 fixes C₀.✓ Proved
  5. \[ \frac{x^{5}}{5} - \frac{11 x}{3} + \frac{4 x^{\frac{5}{2}}}{15} - \frac{4}{5} = \frac{4 x^{\frac{5}{2}}}{15} + \frac{x^{5}}{5} - \frac{11 x}{3} - \frac{4}{5} \]
    The solution.✓ Proved
Answer \( f(x) = \frac{4 x^{\frac{5}{2}}}{15} + \frac{x^{5}}{5} - \frac{11 x}{3} - \frac{4}{5} \)

✓ 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)
  • gpt-oss:20b: pass 2026-10-07
  • qwen3.6:27b-mlx: pass 2026-10-07
  • gpt-oss:20b: pass 2026-10-07
  • qwen3.6:27b-mlx: pass 2026-10-07

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 2026-10-07 with SymPy 1.14.0.