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Derivative of \( \displaystyle \frac{5 \sqrt{4 x^{2} + 1}}{2} \)

Problem 2.295 · medium

Differentiate \( \displaystyle f(x) = \frac{5 \sqrt{4 x^{2} + 1}}{2} \).
  1. \[ \frac{d}{d x} \frac{5 \sqrt{4 x^{2} + 1}}{2} \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{5 \frac{d}{d x} \sqrt{4 x^{2} + 1}}{2} \]
    constant-multiple rewritePull out the constant factor. Rewrite the square root as a fractional exponent.✓ Proved
  3. \[ = \frac{5 \frac{d}{d x} \left(4 x^{2} + 1\right)}{4 \sqrt{4 x^{2} + 1}} \]
    chain algebraApply the chain rule. Multiply the constants.✓ Proved
  4. \[ = \frac{10 x}{\sqrt{4 x^{2} + 1}} \]
    power algebra simplify rewriteDifferentiate the inner function. Rearrange the terms. Simplify the expression. Convert the negative exponent back to a square root in the denominator.✓ Proved
Answer \( \frac{10 x}{\sqrt{4 x^{2} + 1}} \)

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. The reviewers disagree about how one step is explained; every verdict is in the receipt.

The full receipt
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where 4*x**2 + 1 = 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass
  • deepseek-r1:70b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (12)
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-19
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: fail (style) 2026-09-19 — Step 1 is missing a rule label.
  • gpt-oss:20b: fail (error) 2026-09-19 — Step 6 applies two differentiation rules (constant‑multiple and power) at once and labels the step as "power", which is not a valid single rule from the allowed vocabulary.
  • gpt-oss:20b: pass 2026-09-17
  • 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.