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

Problem 2.1489 · hard

Differentiate \( \displaystyle f(x) = \frac{e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{e^{4 x} \cos{\left(4 x \right)}}{8} \).
  1. \[ \frac{d}{d x} \left(\frac{e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{e^{4 x} \cos{\left(4 x \right)}}{8}\right) \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \frac{e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{d}{d x} \frac{e^{4 x} \cos{\left(4 x \right)}}{8} \]
    sumApply the sum rule.✓ Proved
  3. \[ = \frac{\frac{d}{d x} e^{4 x} \sin{\left(4 x \right)}}{8} - \frac{\frac{d}{d x} e^{4 x} \cos{\left(4 x \right)}}{8} \]
    constant-multiple algebraFactor out the constant 1/8. Factor out 1/8 from the expression.✓ Proved
  4. \[ = \frac{e^{4 x} \frac{d}{d x} \sin{\left(4 x \right)}}{8} - \frac{e^{4 x} \frac{d}{d x} \cos{\left(4 x \right)}}{8} + \frac{\sin{\left(4 x \right)} \frac{d}{d x} e^{4 x}}{8} - \frac{\cos{\left(4 x \right)} \frac{d}{d x} e^{4 x}}{8} \]
    productApply the product rule to both terms.✓ Proved
  5. \[ = \frac{e^{4 x} \sin{\left(4 x \right)}}{2} - \frac{e^{4 x} \cos{\left(4 x \right)}}{2} + \frac{e^{4 x} \frac{d}{d x} \sin{\left(4 x \right)}}{8} - \frac{e^{4 x} \frac{d}{d x} \cos{\left(4 x \right)}}{8} \]
    derivativeDifferentiate the exponential terms.✓ Proved
  6. \[ = e^{4 x} \sin{\left(4 x \right)} \]
    trig algebra algebra simplify simplifyDifferentiate the trigonometric terms. Simplify the expression inside the parentheses. Distribute the negative sign. Combine like terms. Simplify the final expression.✓ Proved
Answer \( e^{4 x} \sin{\left(4 x \right)} \)

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
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: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-04
  • gpt-oss:20b: pass 2026-10-04
  • qwen3.6:27b-mlx: fail (error) 2026-10-04 — Step 5 applies the product rule to two separate terms simultaneously, violating the constraint that each step must change only one thing. Step 6 and Step 7 also combine differentiation of exponential and trigonometric terms (requiring the chain rule) into single steps labeled 'derivative' and 'trig' respectively, which is logically incomplete as it skips the explicit application of the chain rule for the inner functions.
  • gpt-oss:20b: fail (style) 2026-10-04 — Step 5 applies the product rule to both terms in one line, combining two separate product-rule applications into a single step, which violates the rule that each step must change only one thing.

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 2026-10-04 with SymPy 1.14.0.