Derivative of \( \displaystyle \left(x + 2\right)^{x + 2} \)
Problem 2.321 · medium
Differentiate \( \displaystyle f(x) = \left(x + 2\right)^{x + 2} \).
- \[ \frac{d}{d x} \left(x + 2\right)^{x + 2} \]derivative rewriteStart with the derivative of the function. Rewrite the base and exponent using the exponential and logarithm functions.✓ Proved
- \[ = \frac{d}{d x} e^{\left(x + 2\right) \ln{\left(x + 2 \right)}} \]simplifySimplify the expression inside the derivative.≈ Checked numerically
- \[ = e^{\left(x + 2\right) \ln{\left(x + 2 \right)}} \frac{d}{d x} \left(x + 2\right) \ln{\left(x + 2 \right)} \]chainApply the chain rule.✓ Proved
- \[ = \left(\left(x + 2\right) \frac{d}{d x} \ln{\left(x + 2 \right)} + \ln{\left(x + 2 \right)} \frac{d}{d x} \left(x + 2\right)\right) e^{\left(x + 2\right) \ln{\left(x + 2 \right)}} \]productApply the product rule to the inner expression.✓ Proved
- \[ = \left(\left(x + 2\right) \frac{d}{d x} \ln{\left(x + 2 \right)} + \ln{\left(x + 2 \right)}\right) e^{\left(x + 2\right) \ln{\left(x + 2 \right)}} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = \left(\ln{\left(x + 2 \right)} + 1\right) e^{\left(x + 2\right) \ln{\left(x + 2 \right)}} \]derivative algebraDifferentiate the second part of the product. Simplify the expression inside the parentheses.✓ Proved
- \[ = \left(x + 2\right)^{x + 2} \left(\ln{\left(x + 2 \right)} + 1\right) \]rewriteConvert the exponential form back to the original power form.≈ Checked numerically
Answer \( \left(x + 2\right)^{x + 2} \left(\log{\left(x + 2 \right)} + 1\right) \)
✓ Nihil obstat Lines: 8 proved, 2 checked numerically. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation.
The full receipt
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 3 | ≈ Checked numerically | sympy 1.14.0 | sympy 1.14.0: simplify left ((x + 2)**(x + 2) - exp((x + 2)*log(x + 2)))*(log(x + 2) + 1); numeric agreement only, at 24 of 24 sampled points log is undefined for non-positive arguments |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 9 | ≈ Checked numerically | sympy 1.14.0 | sympy 1.14.0: simplify left (-(x + 2)**(x + 2) + exp((x + 2)*log(x + 2)))*(log(x + 2) + 1); numeric agreement only, at 24 of 24 sampled points log is undefined for non-positive arguments |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passdeepseek-r1:70b: passqwen3.6:27b-mlx: pass
Every verdict on record (13)
qwen3.6:27b-mlx: pass 2026-09-20gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies logarithmic differentiation via rewriting, adhering to the one-rule-per-step constraint and using valid labels from the fixed vocabulary.gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-19deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19qwen3.6:27b-mlx: pass 2026-09-19deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19qwen3.6:27b-mlx: pass 2026-09-18deepseek-r1:70b: pass 2026-09-18gpt-oss:20b: pass 2026-09-18
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.