Derivative of \( \displaystyle \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \)
Problem 2.712 · medium
Differentiate \( \displaystyle f(x) = \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \).
- \[ \frac{d}{d x} \frac{\sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \]constantStart with the derivative of the function.✓ Proved
- \[ = \frac{\frac{d}{d x} \sqrt{\left(4 x - 3\right)^{2} + 1}}{2} \]constant-multiple rewriteMove the constant factor outside. Rewrite the square root as a power.✓ Proved
- \[ = \frac{\frac{d}{d x} \left(\left(4 x - 3\right)^{2} + 1\right)}{4 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]chainApply the chain rule.✓ Proved
- \[ = \frac{\frac{d}{d x} \left(4 x - 3\right)^{2}}{4 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]sum rewriteDifferentiate the sum inside the parenthesis. Rewrite the power using the exponential-logarithm identity.✓ Proved
- \[ = \frac{\left(4 x - 3\right)^{2} \frac{d}{d x} \ln{\left(4 x - 3 \right)}}{2 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]exponential rewriteDifferentiate the exponential function. Substitute the exponential back to its power form.✓ Proved
- \[ = \frac{\left(4 x - 3\right) \frac{d}{d x} \left(4 x - 3\right)}{2 \sqrt{\left(4 x - 3\right)^{2} + 1}} \]logarithmicDifferentiate the natural logarithm.✓ Proved
- \[ = \frac{2 \left(4 x - 3\right)}{\sqrt{\left(4 x - 3\right)^{2} + 1}} \]algebraSimplify the algebraic terms.✓ Proved
- \[ = \frac{8 x - 6}{\sqrt{\left(4 x - 3\right)^{2} + 1}} \]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
| 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 undefined where (4*x - 3)**2 + 1 = 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 log is undefined for non-positive arguments |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments undefined where (4*x - 3)**2 + 1 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments undefined where (4*x - 3)**2 + 1 = 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 undefined where (4*x - 3)**2 + 1 = 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-21gpt-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.