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Derivative of \( \displaystyle x e^{4 x} - \frac{e^{4 x}}{4} \)

Problem 2.1751 · hard

Differentiate \( \displaystyle f(x) = x e^{4 x} - \frac{e^{4 x}}{4} \).
  1. \[ \frac{d}{d x} \left(x e^{4 x} - \frac{e^{4 x}}{4}\right) \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} x e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]
    sum constantApply the sum rule. Factor out the constant 1/4.✓ Proved
  3. \[ = x \frac{d}{d x} e^{4 x} + e^{4 x} \frac{d}{d x} x - \frac{d}{d x} \frac{e^{4 x}}{4} \]
    productApply the product rule to the first term.✓ Proved
  4. \[ = x \frac{d}{d x} e^{4 x} + e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]
    derivative simplifyDifferentiate x. Simplify the first term.✓ Proved
  5. \[ = 4 x e^{4 x} + e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]
    chain algebraDifferentiate exp(4*x) using the chain rule. Simplify the second term.✓ Proved
  6. \[ = 4 x e^{4 x} \]
    chain algebra simplifyDifferentiate the last term using the chain rule. Simplify the last term. Combine like terms.✓ Proved
Answer \( 4 x e^{4 x} \)

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
11✓ 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: fail (error) — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would pull 1/4 out of the derivative); it merely rewrites the term algebraically, so the label is incorrect. Step 9 is labeled 'chain' but applies the constant multiple rule and the chain rule simultaneously to the term 1/4 * exp(4*x), violating the one-rule-per-step constraint.
Every verdict on record (4)
  • gpt-oss:20b: pass 2026-10-07
  • qwen3.6:27b-mlx: fail (error) 2026-10-07 — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would pull 1/4 out of the derivative); it merely rewrites the term algebraically, so the label is incorrect. Step 9 is labeled 'chain' but applies the constant multiple rule and the chain rule simultaneously to the term 1/4 * exp(4*x), violating the one-rule-per-step constraint.
  • gpt-oss:20b: pass 2026-10-07
  • qwen3.6:27b-mlx: fail (error) 2026-10-07 — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would factor out 1/4); it merely rewrites the term, so the label is incorrect. Step 9 is labeled 'chain' but applies both the constant multiple rule and the chain rule simultaneously, violating the one-rule-per-step constraint.

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 2026-10-07 with SymPy 1.14.0.