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

Problem 2.319 · hard

Differentiate \( \displaystyle f(x) = \frac{\left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1}}{2} \).
  1. \[ \frac{d}{d x} \frac{\left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1}}{2} \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) \frac{d}{d x} \frac{e^{2 x - 1}}{2} + \frac{e^{2 x - 1} \frac{d}{d x} \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right)}{2} \]
    productApply the product rule.✓ Proved
  3. \[ = \frac{\left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} \frac{d}{d x} \left(2 x - 1\right)}{2} + \frac{e^{2 x - 1} \frac{d}{d x} \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right)}{2} \]
    chainApply the chain rule to the exponential part.✓ Proved
  4. \[ = \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} + \frac{e^{2 x - 1} \frac{d}{d x} \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right)}{2} \]
    derivative algebraDifferentiate the inner function 2*x - 1. Simplify the constant factor 2/2.✓ Proved
  5. \[ = \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} + \frac{\left(\frac{d}{d x} \sin{\left(2 x - 1 \right)} - \frac{d}{d x} \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1}}{2} \]
    sumDistribute the derivative over the subtraction.✓ Proved
  6. \[ = \frac{\left(\sin{\left(2 x - 1 \right)} \frac{d}{d x} \left(2 x - 1\right) + \cos{\left(2 x - 1 \right)} \frac{d}{d x} \left(2 x - 1\right)\right) e^{2 x - 1}}{2} + \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} \]
    trigDifferentiate the sine and cosine terms using the chain rule.✓ Proved
  7. \[ = \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} + \frac{\left(2 \sin{\left(2 x - 1 \right)} + 2 \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1}}{2} \]
    derivative algebraDifferentiate the inner function 2*x - 1. Factor out the 2.✓ Proved
  8. \[ = \left(\sin{\left(2 x - 1 \right)} - \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} + \left(\sin{\left(2 x - 1 \right)} + \cos{\left(2 x - 1 \right)}\right) e^{2 x - 1} \]
    algebraCancel the 2 in the numerator and denominator.✓ Proved
  9. \[ = 2 e^{2 x - 1} \sin{\left(2 x - 1 \right)} \]
    algebra simplify algebraFactor out the common exponential term. Combine like terms inside the parentheses. Rearrange the terms for the final answer.✓ Proved
Answer \( 2 e^{2 x - 1} \sin{\left(2 x - 1 \right)} \)

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
12✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
13✓ 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 — 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.
Every verdict on record (12)
  • qwen3.6:27b-mlx: pass 2026-09-20 — 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.
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-19 — The solution correctly applies differentiation rules and algebraic simplifications in a step-by-step manner. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: fail (error) 2026-09-19 — Step 7 applies both the trig derivative rule and the chain rule in a single step, violating the rule‑by‑step granularity requirement.
  • qwen3.6:27b-mlx: pass 2026-09-19 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels accurately describe the operations performed, and the final result is correct.
  • deepseek-r1:70b: fail (style) 2026-09-19 — Step 1 is missing a rule label.
  • gpt-oss:20b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-17
  • deepseek-r1:70b: pass 2026-09-17

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.