Derivative of \( \displaystyle \left(x + \frac{1}{3}\right) e^{3 x + 2} \)
Problem 2.660 · medium
Differentiate \( \displaystyle f(x) = \left(x + \frac{1}{3}\right) e^{3 x + 2} \).
- \[ \frac{d}{d x} \left(x + \frac{1}{3}\right) e^{3 x + 2} \]derivativeStart with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} \left(x e^{3 x + 2} + \frac{e^{3 x + 2}}{3}\right) \]sumDistribute the first term.✓ Proved
- \[ = \frac{d}{d x} x e^{3 x + 2} + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]sumApply the sum rule.✓ Proved
- \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} \frac{d}{d x} x + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]productApply the product rule to the first term.✓ Proved
- \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} + \frac{d}{d x} \frac{e^{3 x + 2}}{3} \]derivativeDifferentiate x.✓ Proved
- \[ = x \frac{d}{d x} e^{3 x + 2} + e^{3 x + 2} + \frac{\frac{d}{d x} e^{3 x + 2}}{3} \]constant-multipleFactor out the constant 1/3.✓ Proved
- \[ = 3 x e^{3 x + 2} + 2 e^{3 x + 2} \]chain algebra algebraApply the chain rule to the exponential terms. Simplify the constant multiplication. Combine like terms.✓ Proved
- \[ = \left(3 x + 2\right) e^{3 x + 2} \]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
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passqwen3.6:27b-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 2026-09-21qwen3.6:27b-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.