Derivative of \( \displaystyle 5 x \left(25 x^{2} - 15 x + 3\right) \)
Problem 2.1016 · hard
Differentiate \( \displaystyle f(x) = 5 x \left(25 x^{2} - 15 x + 3\right) \).
- \[ \frac{d}{d x} 5 x \left(25 x^{2} - 15 x + 3\right) \]Start with the derivative of the function.✓ Proved
- \[ = 5 \frac{d}{d x} x \left(25 x^{2} - 15 x + 3\right) \]constant-multiplePull out the constant factor 5.✓ Proved
- \[ = 5 x \frac{d}{d x} \left(25 x^{2} - 15 x + 3\right) + 5 \left(25 x^{2} - 15 x + 3\right) \frac{d}{d x} x \]productApply the product rule.✓ Proved
- \[ = 125 x^{2} + 5 x \left(\frac{d}{d x} 3 - \frac{d}{d x} 15 x + \frac{d}{d x} 25 x^{2}\right) - 75 x + 15 \]algebraDistribute the derivative across the sum.✓ Proved
- \[ = 125 x^{2} + 5 x \left(\frac{d}{d x} 25 x^{2} - 15\right) - 75 x + 15 \]derivativeDifferentiate the individual terms.✓ Proved
- \[ = 125 x^{2} + 5 x \left(50 x - 15\right) - 75 x + 15 \]derivativeEvaluate the derivative of 25*x**2.✓ Proved
- \[ = 375 x^{2} - 150 x + 15 \]algebra algebra algebraDistribute x into the parentheses. Combine like terms inside the parentheses. Distribute the constant 5 to get the final answer.✓ Proved
Answer \( 15 \left(5 x - 1\right)^{2} \)
✓ 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 |
| 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: fail (style) — Step 4 applies the derivative of a sum (a derivative rule), but is labeled "algebra". The correct label should be "derivative" (or "sum").qwen3.6:27b-mlx: pass — The solution correctly applies the constant multiple, product, and sum rules in a step-by-step manner. The algebraic simplifications are correct, and the final result matches the stated answer.
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-09-27 — The solution correctly applies the constant multiple, product, and sum rules in a step-by-step manner. The algebraic simplifications are correct, and the final result matches the stated answer.gpt-oss:20b: fail (style) 2026-09-27 — Step 4 applies the derivative of a sum (a derivative rule), but is labeled "algebra". The correct label should be "derivative" (or "sum").qwen3.6:27b-mlx: pass 2026-09-27gpt-oss:20b: fail (style) 2026-09-27 — Step 4 applies the linearity of the derivative (splitting the derivative of a sum into the sum of derivatives), but it is labeled "algebra". The correct label for that step should be "derivative".
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 2026-09-27 with SymPy 1.14.0.