Derivative of \( \displaystyle \frac{\sqrt{4 x + 1}}{4 x + 2} \)
Problem 2.441 · hard
Differentiate \( \displaystyle f(x) = \frac{\sqrt{4 x + 1}}{4 x + 2} \).
- \[ \frac{d}{d x} \frac{\sqrt{4 x + 1}}{4 x + 2} \]rewriteStart with the derivative of the function. Rewrite the denominator using a negative exponent.✓ Proved
- \[ = \sqrt{4 x + 1} \frac{d}{d x} \frac{1}{4 x + 2} + \frac{\frac{d}{d x} \sqrt{4 x + 1}}{4 x + 2} \]product rewriteApply the product rule. Rewrite the square root as a fractional power.✓ Proved
- \[ = \sqrt{4 x + 1} \frac{d}{d x} \frac{1}{4 x + 2} + \frac{2}{\sqrt{4 x + 1} \left(4 x + 2\right)} \]chainApply the chain rule to the first term.✓ Proved
- \[ = - \frac{4 \sqrt{4 x + 1}}{\left(4 x + 2\right)^{2}} + \frac{2}{\sqrt{4 x + 1} \left(4 x + 2\right)} \]chain constant-multiple algebraApply the chain rule to the second term. Simplify the constants. Distribute the exponents.✓ Proved
- \[ = - \frac{8 x}{\sqrt{4 x + 1} \left(4 x + 2\right)^{2}} \]algebra algebra algebra simplifyFind a common denominator. Simplify the numerator. Distribute the 4. Combine like terms.✓ Proved
Answer \( - \frac{2 x}{\left(2 x + 1\right)^{2} \sqrt{4 x + 1}} \)
✓ 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 undefined where 4*x + 2 = 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| 12 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 2 = 0 undefined where 4*x + 1 = 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 undefined where 2*x + 1 = 0 undefined where 4*x + 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 (6)
qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-20gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20gpt-oss:20b: pass 2026-09-20
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.