∫Calc Practice

Derivative of \( \displaystyle - x \ln{\left(5 x + 2 \right)} + x - \frac{2 \ln{\left(5 x + 2 \right)}}{5} \)

Problem 2.947 · hard

Differentiate \( \displaystyle f(x) = - x \ln{\left(5 x + 2 \right)} + x - \frac{2 \ln{\left(5 x + 2 \right)}}{5} \).
  1. \[ \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)} + x - \frac{2 \ln{\left(5 x + 2 \right)}}{5}\right) \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} x + \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) + \frac{d}{d x} \left(- \frac{2 \ln{\left(5 x + 2 \right)}}{5}\right) \]
    sumApply the sum rule to separate the terms.✓ Proved
  3. \[ = \frac{d}{d x} x + \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) - \frac{d}{d x} \frac{2 \ln{\left(5 x + 2 \right)}}{5} \]
    algebraRewrite the subtraction as addition of a negative term.✓ Proved
  4. \[ = \frac{d}{d x} x + \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) - \frac{2 \frac{d}{d x} \ln{\left(5 x + 2 \right)}}{5} \]
    constant-multiplePull the constant factor out of the derivative.✓ Proved
  5. \[ = \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) - \frac{2 \frac{d}{d x} \ln{\left(5 x + 2 \right)}}{5} + 1 \]
    derivativeDifferentiate the term x.✓ Proved
  6. \[ = \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) + 1 - \frac{2 \frac{d}{d x} \left(5 x + 2\right)}{5 \left(5 x + 2\right)} \]
    chainApply the chain rule to the logarithm.✓ Proved
  7. \[ = \frac{d}{d x} \left(- x \ln{\left(5 x + 2 \right)}\right) + 1 - \frac{2}{5 x + 2} \]
    derivative algebraDifferentiate the inner linear function. Simplify the product of the constants and the fraction.✓ Proved
  8. \[ = - x \frac{d}{d x} \ln{\left(5 x + 2 \right)} + \ln{\left(5 x + 2 \right)} \frac{d}{d x} \left(- x\right) + 1 - \frac{2}{5 x + 2} \]
    productApply the product rule to the first term.✓ Proved
  9. \[ = - \frac{x \frac{d}{d x} \left(5 x + 2\right)}{5 x + 2} - \ln{\left(5 x + 2 \right)} + 1 - \frac{2}{5 x + 2} \]
    derivativeDifferentiate -x.✓ Proved
  10. \[ = - \frac{5 x}{5 x + 2} - \ln{\left(5 x + 2 \right)} + 1 - \frac{2}{5 x + 2} \]
    derivative algebraDifferentiate the inner part of the chain rule again. Simplify the term involving x.✓ Proved
  11. \[ = \frac{- 5 x - 2}{5 x + 2} - \ln{\left(5 x + 2 \right)} + 1 \]
    algebraCombine the fractions with the same denominator.✓ Proved
  12. \[ = - \ln{\left(5 x + 2 \right)} \]
    algebra simplifySimplify the fraction (-5x-2)/(5x+2) to -1. Final simplification.✓ Proved
Answer \( - \ln{\left(5 x + 2 \right)} \)

✓ 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
log is undefined for non-positive arguments
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
11✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
12✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
13✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
14✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where 5*x + 2 = 0
15✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
log is undefined for non-positive arguments
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 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels accurately reflect the operations performed, and the algebraic simplifications are valid.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-27 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The labels accurately reflect the operations performed, and the algebraic simplifications are valid.
  • gpt-oss:20b: pass 2026-09-27
  • qwen3.6:27b-mlx: pass 2026-09-27 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint and using valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-09-27

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 2026-09-27 with SymPy 1.14.0.