Derivative of \( \displaystyle \left(x - 2\right)^{x - 3} \)
Problem 2.461 · medium
Differentiate \( \displaystyle f(x) = \left(x - 2\right)^{x - 3} \).
- \[ \frac{d}{d x} \left(x - 2\right)^{x - 3} \]derivativeStart with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} e^{\left(x - 3\right) \ln{\left(x - 2 \right)}} \]rewriteRewrite the base and exponent using the exponential and logarithm.≈ Checked numerically
- \[ = e^{\left(x - 3\right) \ln{\left(x - 2 \right)}} \frac{d}{d x} \left(x - 3\right) \ln{\left(x - 2 \right)} \]chainApply the chain rule.✓ Proved
- \[ = \left(\left(x - 3\right) \frac{d}{d x} \ln{\left(x - 2 \right)} + \ln{\left(x - 2 \right)} \frac{d}{d x} \left(x - 3\right)\right) e^{\left(x - 3\right) \ln{\left(x - 2 \right)}} \]productApply the product rule to the inner expression.✓ Proved
- \[ = \left(\left(x - 3\right) \frac{d}{d x} \ln{\left(x - 2 \right)} + \ln{\left(x - 2 \right)}\right) e^{\left(x - 3\right) \ln{\left(x - 2 \right)}} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = \left(\frac{x - 3}{x - 2} + \ln{\left(x - 2 \right)}\right) e^{\left(x - 3\right) \ln{\left(x - 2 \right)}} \]derivativeDifferentiate the second part of the product.✓ Proved
- \[ = \left(x - 2\right)^{x - 3} \left(\frac{x - 3}{x - 2} + \ln{\left(x - 2 \right)}\right) \]simplifyConvert the exponential back to its original form.≈ Checked numerically
- \[ = \left(x - 2\right)^{x - 3} \left(\ln{\left(x - 2 \right)} + 1 - \frac{1}{x - 2}\right) \]algebraSplit the fraction inside the parentheses.✓ Proved
- \[ = \left(x - 2\right)^{x - 3} \left(\frac{x - 3}{x - 2} + \ln{\left(x - 2 \right)}\right) \]simplifyKeep the fraction form for the final answer.✓ Proved
Answer \( \left(x - 2\right)^{x - 3} \left(\frac{x - 3}{x - 2} + \log{\left(x - 2 \right)}\right) \)
✓ 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 | ≈ Checked numerically | sympy 1.14.0 | sympy 1.14.0: simplify left ((x - 2)**(x - 3)*(x + (x - 2)*log(x - 2) - 3) + (-x - (x - 2)*log(x - 2) + 3)*exp((x - 3)*log(x - 2)))/(x - 2); numeric agreement only, at 24 of 24 sampled points log is undefined for non-positive arguments |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 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 undefined where x - 2 = 0 |
| 7 | ≈ Checked numerically | sympy 1.14.0 | sympy 1.14.0: simplify left ((x - 2)**(x - 3)*(-x - (x - 2)*log(x - 2) + 3) + (x + (x - 2)*log(x - 2) - 3)*exp((x - 3)*log(x - 2)))/(x - 2); numeric agreement only, at 24 of 24 sampled points log is undefined for non-positive arguments undefined where x - 2 = 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments undefined where x - 2 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments undefined where x - 2 = 0 |
| 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 undefined where x - 2 = 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass
Every verdict on record (6)
qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies logarithmic differentiation, 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 2026-09-20 — The solution correctly applies logarithmic differentiation, adhering to the one-rule-per-step constraint and using valid labels from the fixed vocabulary.gpt-oss:20b: pass 2026-09-20
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.