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Derivative of \( \displaystyle - \frac{\sqrt{2} e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)}}{2} \)

Problem 2.883 · hard

Differentiate \( \displaystyle f(x) = - \frac{\sqrt{2} e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)}}{2} \).
  1. \[ \frac{d}{d x} \left(- \frac{\sqrt{2} e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)}}{2}\right) \]
    Start with the derivative of the function.✓ Proved
  2. \[ = - \frac{\sqrt{2} \frac{d}{d x} e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)}}{2} \]
    constant-multiplePull out the constant factor.✓ Proved
  3. \[ = - \frac{\sqrt{2} \left(e^{x + 2} \frac{d}{d x} \cos{\left(x + \frac{\pi}{4} + 2 \right)} + \cos{\left(x + \frac{\pi}{4} + 2 \right)} \frac{d}{d x} e^{x + 2}\right)}{2} \]
    productApply the product rule.✓ Proved
  4. \[ = - \frac{\sqrt{2} \left(e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)} + e^{x + 2} \frac{d}{d x} \cos{\left(x + \frac{\pi}{4} + 2 \right)}\right)}{2} \]
    derivativeDifferentiate the first part of the product.✓ Proved
  5. \[ = - \frac{\sqrt{2} \left(- e^{x + 2} \sin{\left(x + \frac{\pi}{4} + 2 \right)} + e^{x + 2} \cos{\left(x + \frac{\pi}{4} + 2 \right)}\right)}{2} \]
    derivativeDifferentiate the second part of the product.✓ Proved
  6. \[ = - \frac{\sqrt{2} \left(- \sin{\left(x + \frac{\pi}{4} + 2 \right)} + \cos{\left(x + \frac{\pi}{4} + 2 \right)}\right) e^{x + 2}}{2} \]
    algebra rewrite simplifyFactor out the common term exp(x + 2). Use trigonometric identities if needed, but here we simplify the expression structure. The expression is already in its simplest form.✓ Proved
Answer \( e^{x + 2} \sin{\left(x + 2 \right)} \)

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
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) — The solution fails to reach the stated answer. Step 7 and 8 are circular or incorrect manipulations that do not simplify the expression to exp(x+2)*sin(x+2). Specifically, the term in parentheses is cos(x+2+pi/4) - sin(x+2+pi/4), which simplifies to -sqrt(2)sin(x+2), but the steps shown do not perform this simplification correctly or at all, leaving the expression in a form that does not match the stated answer.
Every verdict on record (4)
  • qwen3.6:27b-mlx: fail (error) 2026-09-26 — The solution fails to reach the stated answer. Step 7 and 8 are circular or incorrect manipulations that do not simplify the expression to exp(x+2)*sin(x+2). Specifically, the term in parentheses is cos(x+2+pi/4) - sin(x+2+pi/4), which simplifies to -sqrt(2)sin(x+2), but the steps shown do not perform this simplification correctly or at all, leaving the expression in a form that does not match the stated answer.
  • gpt-oss:20b: pass 2026-09-26
  • qwen3.6:27b-mlx: fail (error) 2026-09-26 — The solution fails to reach the stated answer. Step 7 and 8 are circular and do not simplify the expression to exp(x+2)*sin(x+2). The intermediate result -sqrt(2)/2 * exp(x + 2) * (cos(x + pi/4 + 2) - sin(x + pi/4 + 2)) is not algebraically equivalent to the stated answer without further trigonometric simplification which is missing or incorrect.
  • gpt-oss:20b: pass 2026-09-26

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.