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Derivative of \( \displaystyle \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \)

Problem 2.712 · medium

Differentiate \( \displaystyle f(x) = \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \).
  1. \[ \frac{d}{d x} \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \]
    constantStart with the derivative of the function.✓ Proved
  2. \[ = \frac{\frac{d}{d x} \sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \]
    constant-multiple rewriteMove the constant factor outside. Rewrite the square root as a power.✓ Proved
  3. \[ = \frac{\frac{d}{d x} \left(\left(4 x - 3\right)^{2} + 1\right)}{4 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    chainApply the chain rule.✓ Proved
  4. \[ = \frac{\frac{d}{d x} \left(4 x - 3\right)^{2}}{4 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    sum rewriteDifferentiate the sum inside the parenthesis. Rewrite the power using the exponential-logarithm identity.✓ Proved
  5. \[ = \frac{\left(4 x - 3\right)^{2} \frac{d}{d x} \ln{\left(4 x - 3 \right)}}{2 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    exponential rewriteDifferentiate the exponential function. Substitute the exponential back to its power form.✓ Proved
  6. \[ = \frac{\left(4 x - 3\right) \frac{d}{d x} \left(4 x - 3\right)}{2 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    logarithmicDifferentiate the natural logarithm.✓ Proved
  7. \[ = \frac{2 \left(4 x - 3\right)}{\sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    algebraSimplify the algebraic terms.✓ Proved
  8. \[ = \frac{8 x - 6}{\sqrt{\left(4 x - 3\right)^{2} + 1}} \]
    simplifyFinal simplified form.✓ Proved
Answer \( \frac{2 \left(4 x - 3\right)}{\sqrt{\left(4 x - 3\right)^{2} + 1}} \)

✓ 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
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 - 3)**2 + 1 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
log is undefined for non-positive arguments
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where (4*x - 3)**2 + 1 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
log is undefined for non-positive arguments
undefined where (4*x - 3)**2 + 1 = 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
11✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where (4*x - 3)**2 + 1 = 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-oss:20b: pass 2026-09-21

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.