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Derivative of \( \displaystyle \frac{\operatorname{atan}{\left(3 x - 1 \right)}}{3} \)

Problem 2.644 · medium

Differentiate \( \displaystyle f(x) = \frac{\operatorname{atan}{\left(3 x - 1 \right)}}{3} \).
  1. \[ \frac{d}{d x} \frac{\operatorname{atan}{\left(3 x - 1 \right)}}{3} \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{\frac{d}{d x} \operatorname{atan}{\left(3 x - 1 \right)}}{3} \]
    constant-multiplePull out the constant factor 1/3.✓ Proved
  3. \[ = \frac{\frac{d}{d x} \left(3 x - 1\right)}{3 \left(\left(3 x - 1\right)^{2} + 1\right)} \]
    chainApply the chain rule to the arctangent function.✓ Proved
  4. \[ = \frac{1}{\left(3 x - 1\right)^{2} + 1} \]
    derivative simplifyDifferentiate the inner linear function. Simplify the expression by canceling the 3.✓ Proved
Answer \( \frac{1}{\left(3 x - 1\right)^{2} + 1} \)

✓ 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
undefined where (3*x - 1)**2 + 1 = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (3*x - 1)**2 + 1 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (3*x - 1)**2 + 1 = 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where (3*x - 1)**2 + 1 = 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 2026-09-21
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-oss:20b: pass 2026-09-21

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.