∫Calc Practice

Derivative of \( \displaystyle - 5 x + \left(5 x + 5\right) \ln{\left(x + 1 \right)} \)

Problem 2.2016 · hard Beautiful

Differentiate \( \displaystyle f(x) = - 5 x + \left(5 x + 5\right) \ln{\left(x + 1 \right)} \).
  1. \[ \frac{d}{d x} \left(- 5 x + \left(5 x + 5\right) \ln{\left(x + 1 \right)}\right) \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \left(- 5 x\right) + \frac{d}{d x} \left(5 x + 5\right) \ln{\left(x + 1 \right)} \]
    sum algebraApply the sum rule. Factor out the constant 5.✓ Proved
  3. \[ = \frac{d}{d x} \left(- 5 x\right) + 5 \frac{d}{d x} \left(x + 1\right) \ln{\left(x + 1 \right)} \]
    constant-multipleApply the constant multiple rule.✓ Proved
  4. \[ = 5 \left(x + 1\right) \frac{d}{d x} \ln{\left(x + 1 \right)} + 5 \ln{\left(x + 1 \right)} \frac{d}{d x} \left(x + 1\right) + \frac{d}{d x} \left(- 5 x\right) \]
    productApply the product rule to the second term.✓ Proved
  5. \[ = 5 \left(x + 1\right) \frac{d}{d x} \ln{\left(x + 1 \right)} + 5 \ln{\left(x + 1 \right)} + \frac{d}{d x} \left(- 5 x\right) \]
    derivativeDifferentiate the first part of the product.✓ Proved
  6. \[ = 5 \ln{\left(x + 1 \right)} + \frac{d}{d x} \left(- 5 x\right) + 5 \]
    logarithmic algebra algebraDifferentiate the natural logarithm. Simplify the fraction. Distribute the 5.✓ Proved
  7. \[ = 5 \ln{\left(x + 1 \right)} \]
    derivative simplifyDifferentiate the first term. Combine the constant terms.✓ Proved
Answer \( 5 \ln{\left(x + 1 \right)} \)

✓ 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
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
11✓ 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 algebraic manipulation in step 3 is valid and properly labeled.
Every verdict on record (4)
  • gpt-oss:20b: pass 2026-10-10
  • qwen3.6:27b-mlx: pass 2026-10-10 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. The algebraic manipulation in step 3 is valid and properly labeled.
  • gpt-oss:20b: pass 2026-10-10
  • qwen3.6:27b-mlx: pass 2026-10-10

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 2026-10-10 with SymPy 1.14.0.