Derivative of \( \displaystyle x \left(16 x^{2} + 12 x + 3\right) \)
Problem 2.208 · hard
Differentiate \( \displaystyle f(x) = x \left(16 x^{2} + 12 x + 3\right) \).
- \[ \frac{d}{d x} x \left(16 x^{2} + 12 x + 3\right) \]derivativeStart with the derivative of the function.✓ Proved
- \[ = x \frac{d}{d x} \left(16 x^{2} + 12 x + 3\right) + \left(16 x^{2} + 12 x + 3\right) \frac{d}{d x} x \]productApply the product rule.✓ Proved
- \[ = 16 x^{2} + x \left(\frac{d}{d x} 3 + \frac{d}{d x} 12 x + \frac{d}{d x} 16 x^{2}\right) + 12 x + 3 \]derivativeDifferentiate the terms in the second part of the product rule.✓ Proved
- \[ = 16 x^{2} + x \left(32 x + 12\right) + 12 x + 3 \]derivative algebraApply the power rule and constant rule to each term. Simplify the expression inside the parentheses.✓ Proved
- \[ = 48 x^{2} + 24 x + 3 \]algebra algebraDistribute x into the parentheses. Combine like terms.✓ Proved
Answer \( 3 \left(4 x + 1\right)^{2} \)
✓ 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
| 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 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 |
| 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: fail (style) — Step 3 applies the sum rule to split the derivative of the polynomial, but is labeled 'derivative'. The label 'sum' is available in the vocabulary and is the specific rule applied to separate the terms.
Every verdict on record (12)
qwen3.6:27b-mlx: fail (style) 2026-09-20 — Step 3 applies the sum rule to split the derivative of the polynomial, but is labeled 'derivative'. The label 'sum' is available in the vocabulary and is the specific rule applied to separate the terms.gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies the product rule, linearity of differentiation, and power rule. Each step changes only one aspect of the expression and uses 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 2026-09-18deepseek-r1:70b: pass 2026-09-18gpt-oss:20b: pass 2026-09-18gpt-oss:20b: pass 2026-09-17deepseek-r1:70b: pass 2026-09-17
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.