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Derivative of \( \displaystyle \left(x + \frac{1}{3}\right) e^{3 x + 2} \)

Problem 2.660 · medium

Differentiate \( \displaystyle f(x) = \left(x + \frac{1}{3}\right) e^{3 x + 2} \).
  1. \[ \frac{d}{d x} \left(x + \frac{1}{3}\right) e^{3 x + 2} \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \left(x e^{3 x + 2} + \frac{e^{3 x + 2}}{3}\right) \]
    sumDistribute the first term.✓ Proved
  3. \[ = \frac{d}{d x} x e^{3 x + 2} + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]
    sumApply the sum rule.✓ Proved
  4. \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} \frac{d}{d x} x + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]
    productApply the product rule to the first term.✓ Proved
  5. \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]
    derivativeDifferentiate x.✓ Proved
  6. \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} + \frac{\frac{d}{d x} e^{3 x + 2}}{3} \]
    constant-multipleFactor out the constant 1/3.✓ Proved
  7. \[ = 3 x e^{3 x + 2} + 2 e^{3 x + 2} \]
    chain algebra algebraApply the chain rule to the exponential terms. Simplify the constant multiplication. Combine like terms.✓ Proved
  8. \[ = \left(3 x + 2\right) e^{3 x + 2} \]
    simplifyFactor out the common exponential term.✓ Proved
Answer \( \left(3 x + 2\right) e^{3 x + 2} \)

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. The reviewers disagree about how one step is explained; every verdict is in the receipt.

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
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
10✓ 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 differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels accurately describe the operations performed.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-21 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels accurately describe the operations performed.
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-mlx: pass 2026-09-21 — The solution correctly applies differentiation rules step-by-step, adhering to the single-change constraint and using valid labels from the fixed vocabulary.
  • gpt-oss:20b: fail (error) 2026-09-21 — Step 7 applies the chain rule to two separate terms in a single step, violating the rule that each step must change only one thing. The label "chain" is also misleading because it covers two distinct applications.

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 2026-09-26 with SymPy 1.14.0.