Derivative of \( \displaystyle 2 x \left(3 x + 2\right) \)
Problem 2.123 · easy
Differentiate \( \displaystyle f(x) = 2 x \left(3 x + 2\right) \).
- \[ \frac{d}{d x} 2 x \left(3 x + 2\right) \]derivativeStart with the derivative of the function.✓ Proved
- \[ = 2 x \frac{d}{d x} \left(3 x + 2\right) + \left(3 x + 2\right) \frac{d}{d x} 2 x \]productApply the product rule.✓ Proved
- \[ = 2 x \frac{d}{d x} \left(3 x + 2\right) + 6 x + 4 \]constant-multipleFactor out the constant 2 from the first term.✓ Proved
- \[ = 2 x \left(\frac{d}{d x} 2 + \frac{d}{d x} 3 x\right) + 6 x + 4 \]sumApply the sum rule to the second term.✓ Proved
- \[ = 2 x \left(\frac{d}{d x} 2 + 3\right) + 6 x + 4 \]derivativeDifferentiate 3*x.✓ Proved
- \[ = 12 x + 4 \]derivative algebra algebra algebraDifferentiate the constant 2. Simplify the expression. Distribute the 2. Combine like terms.✓ Proved
Answer \( 12 x + 4 \)
✓ 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 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 9 | ✓ 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: pass
Every verdict on record (15)
qwen3.6:27b-mlx: pass 2026-09-20gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20gpt-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 2026-09-18gpt-oss:20b: fail 2026-09-17 — Step 3 mislabels the operation as a constant‑multiple rule and the note claims to factor out a constant, but it actually evaluates the derivative of 2*x. The rule label and explanatory note do not match the action performed.deepseek-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.