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Derivative of \( \displaystyle \frac{3 e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{3 e^{4 x} \cos{\left(4 x \right)}}{8} \)

Problem 2.1856 · hard

Differentiate \( \displaystyle f(x) = \frac{3 e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{3 e^{4 x} \cos{\left(4 x \right)}}{8} \).
  1. \[ \frac{d}{d x} \left(\frac{3 e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{3 e^{4 x} \cos{\left(4 x \right)}}{8}\right) \]
    derivative constant-multipleStart with the derivative of the function. Factor out the constant 3/8 from both terms.✓ Proved
  2. \[ = \frac{3 \frac{d}{d x} e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{3 \frac{d}{d x} e^{4 x} \cos{\left(4 x \right)}}{8} \]
    sumApply the sum rule for derivatives.✓ Proved
  3. \[ = - \frac{3 e^{4 x} \frac{d}{d x} \cos{\left(4 x \right)}}{8} - \frac{3 \cos{\left(4 x \right)} \frac{d}{d x} e^{4 x}}{8} + \frac{3 \frac{d}{d x} e^{4 x} \sin{\left(4 x \right)}}{8} \]
    productApply the product rule to the second term.✓ Proved
  4. \[ = \frac{3 e^{4 x} \frac{d}{d x} \sin{\left(4 x \right)}}{8} - \frac{3 e^{4 x} \frac{d}{d x} \cos{\left(4 x \right)}}{8} + \frac{3 \sin{\left(4 x \right)} \frac{d}{d x} e^{4 x}}{8} - \frac{3 \cos{\left(4 x \right)} \frac{d}{d x} e^{4 x}}{8} \]
    productApply the product rule to the first term.✓ Proved
  5. \[ = 3 e^{4 x} \sin{\left(4 x \right)} \]
    chain algebra algebra simplify simplifyDifferentiate the exponential and trigonometric functions using the chain rule. Distribute the negative sign. Simplify the double negative. Combine like terms. Final simplification.✓ Proved
Answer \( 3 e^{4 x} \sin{\left(4 x \right)} \)

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
Every verdict on record (4)
  • gpt-oss:20b: pass 2026-10-08
  • qwen3.6:27b-mlx: pass 2026-10-08
  • gpt-oss:20b: fail (error) 2026-10-08 — Step 6 applies several chain‑rule substitutions at once (exp(4x), sin(4x), and cos(4x)), violating the rule that each step must change only one thing.
  • qwen3.6:27b-mlx: pass 2026-10-08 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels used are appropriate for the operations performed.

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 2026-10-08 with SymPy 1.14.0.