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Derivative of \( \displaystyle x \left(- 16 x^{2} + 36 x - 27\right) \)

Problem 2.1259 · hard

Differentiate \( \displaystyle f(x) = x \left(- 16 x^{2} + 36 x - 27\right) \).
  1. \[ \frac{d}{d x} x \left(- 16 x^{2} + 36 x - 27\right) \]
    Start with the derivative of the function.✓ Proved
  2. \[ = x \frac{d}{d x} \left(- 16 x^{2} + 36 x - 27\right) + \left(- 16 x^{2} + 36 x - 27\right) \frac{d}{d x} x \]
    productApply the product rule.✓ Proved
  3. \[ = - 16 x^{2} + x \frac{d}{d x} \left(- 16 x^{2} + 36 x - 27\right) + 36 x - 27 \]
    derivative constant-multipleDifferentiate the first part of the product. Simplify the derivative of x.✓ Proved
  4. \[ = - 16 x^{2} + x \left(36 - 32 x\right) + 36 x - 27 \]
    derivativeDifferentiate the polynomial term by term.✓ Proved
  5. \[ = - 48 x^{2} + 72 x - 27 \]
    algebra simplifyDistribute x into the second term. Combine like terms.✓ Proved
Answer \( - 48 x^{2} + 72 x - 27 \)

✓ 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
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass — The solution correctly applies the product rule and standard differentiation rules. Each step isolates a single operation, and the labels accurately reflect the rules applied.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-29 — The solution correctly applies the product rule and standard differentiation rules. Each step isolates a single operation, and the labels accurately reflect the rules applied.
  • gpt-oss:20b: pass 2026-09-29
  • qwen3.6:27b-mlx: pass 2026-09-29
  • gpt-oss:20b: fail (style) 2026-09-29 — Step 4 incorrectly labels the simplification of 1*(-16*x**2 + 36*x - 27) as "constant-multiple"; it is a plain algebraic simplification.

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 2026-09-29 with SymPy 1.14.0.