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Derivative of \( \displaystyle \frac{\left(4 x - 1\right) e^{4 x}}{2} \)

Problem 2.15 · hard

Differentiate \( \displaystyle f(x) = \frac{\left(4 x - 1\right) e^{4 x}}{2} \).
  1. \[ \frac{d}{d x} \frac{\left(4 x - 1\right) e^{4 x}}{2} \]
    derivative constant-multipleStart with the derivative of the function. Pull out the constant factor 1/2.✓ Proved
  2. \[ = \frac{\frac{d}{d x} \left(4 x - 1\right) e^{4 x}}{2} \]
    constant-multipleMove the constant to the front.✓ Proved
  3. \[ = \frac{\left(4 x - 1\right) \frac{d}{d x} e^{4 x}}{2} + \frac{e^{4 x} \frac{d}{d x} \left(4 x - 1\right)}{2} \]
    productApply the product rule.✓ Proved
  4. \[ = \frac{\left(4 x - 1\right) \frac{d}{d x} e^{4 x}}{2} + 2 e^{4 x} \]
    derivativeDifferentiate the first part of the product.✓ Proved
  5. \[ = 2 \left(4 x - 1\right) e^{4 x} + 2 e^{4 x} \]
    chainApply the chain rule to the exponential term.✓ Proved
  6. \[ = \frac{\left(16 x - 4\right) e^{4 x}}{2} + 2 e^{4 x} \]
    algebraDistribute the 4 into the parentheses.✓ Proved
  7. \[ = 8 x e^{4 x} \]
    algebra simplify simplifyExpand the expression. Combine like terms. Multiply by the constant 1/2.✓ Proved
Answer \( 8 x e^{4 x} \)

✓ 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
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
  • deepseek-r1:70b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (15)
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies the rules in a step-by-step manner, adhering to the one-change-per-step constraint and using valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-19
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-19
  • qwen3.6:27b-mlx: pass 2026-09-18
  • deepseek-r1:70b: pass 2026-09-18
  • gpt-oss:20b: pass 2026-09-18
  • gpt-oss:20b: pass 2026-09-16
  • deepseek-r1:70b: pass 2026-09-16

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.