∫Calc Practice

Derivative of \( \displaystyle \ln{\left(\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)} \right)} \)

Problem 2.1076 · hard

Differentiate \( \displaystyle f(x) = \ln{\left(\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)} \right)} \).
  1. \[ \frac{d}{d x} \ln{\left(\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)} \right)} \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{\frac{d}{d x} \left(\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}\right)}{\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}} \]
    chainApply the chain rule for the natural logarithm.✓ Proved
  3. \[ = \frac{\frac{d}{d x} \tan{\left(5 x + 2 \right)} + \frac{d}{d x} \sec{\left(5 x + 2 \right)}}{\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}} \]
    sumApply the sum rule to the inner terms.✓ Proved
  4. \[ = \frac{5 \tan{\left(5 x + 2 \right)} \sec{\left(5 x + 2 \right)} + 5 \sec^{2}{\left(5 x + 2 \right)}}{\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}} \]
    chainDifferentiate the tangent and secant terms using the chain rule.≈ Checked numerically
  5. \[ = \frac{5 \left(\frac{\tan{\left(5 x + 2 \right)}}{\sec{\left(5 x + 2 \right)}} + 1\right) \sec^{2}{\left(5 x + 2 \right)}}{\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}} \]
    algebraFactor out common terms from the numerator.✓ Proved
  6. \[ = \frac{5 \tan{\left(5 x + 2 \right)} \sec{\left(5 x + 2 \right)} + 5 \sec^{2}{\left(5 x + 2 \right)}}{\tan{\left(5 x + 2 \right)} + \sec{\left(5 x + 2 \right)}} \]
    algebraDistribute the constant factor.✓ Proved
  7. \[ = 5 \sec{\left(5 x + 2 \right)} \]
    algebra simplifyFactor out sec(5*x + 2) from the numerator. Cancel the common term in the numerator and denominator.✓ Proved
Answer \( \frac{5}{\cos{\left(5 x + 2 \right)}} \)
Mind the domain. The answer is also defined at points where f(x) is not. Substituting there gives a number that is not a slope of f.

Lines: 8 proved, 1 checked numerically. 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
log is undefined for non-positive arguments
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
4≈ Checked numericallysympy 1.14.0sympy 1.14.0: simplify left 5*(tan(5*x + 2)**2 - sec(5*x + 2)**2 + 1)/(tan(5*x + 2) + sec(5*x + 2)); numeric agreement only, at 24 of 24 sampled points
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
undefined where sec(5*x + 2) = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
undefined where sec(5*x + 2) = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
tan has poles at odd multiples of pi/2
sec has poles at odd multiples of pi/2
undefined where tan(5*x + 2) + sec(5*x + 2) = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
sec has poles at odd multiples of pi/2
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where cos(5*x + 2) = 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 2026-09-28
  • gpt-oss:20b: pass 2026-09-28
  • qwen3.6:27b-mlx: pass 2026-09-28 — The solution correctly applies the chain rule, sum rule, and standard derivatives. The algebraic simplification steps are valid and correctly labeled.
  • gpt-oss:20b: inconclusive 2026-09-28 — reviewer response could not be parsed: {"verdict":"fail","severity":"error","notes":"The cancellation in step 8 is invalid: \n\\(\\frac{5\\,\\sec(5x+2)(\\sec(5x+2)+\\tan(5x+2))}{\\tan(5x+2)+\\sec(5x+2)}\\) does not simplify to \(5\\sec(5x+

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 2026-09-28 with SymPy 1.14.0.