Derivative of \( \displaystyle x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}} \)
Problem 2.1491 · hard Beautiful
Differentiate \( \displaystyle f(x) = x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}} \).
- \[ \frac{d}{d x} \left(x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}}\right) \]Start with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{d}{d x} \sqrt{1 - x^{2}} \]sum rewriteApply the sum rule. Rewrite the square root as a power.✓ Proved
- \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{\frac{d}{d x} \left(1 - x^{2}\right)}{2 \sqrt{1 - x^{2}}} \]chainApply the chain rule to the second term.✓ Proved
- \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{\frac{d}{d x} \left(- x^{2}\right)}{2 \sqrt{1 - x^{2}}} \]constantApply the sum rule to the inner expression.✓ Proved
- \[ = - \frac{x}{\sqrt{1 - x^{2}}} + \frac{d}{d x} x \operatorname{asin}{\left(x \right)} \]power algebraDifferentiate the term -x**2. Simplify the constants.✓ Proved
- \[ = x \frac{d}{d x} \operatorname{asin}{\left(x \right)} - \frac{x}{\sqrt{1 - x^{2}}} + \operatorname{asin}{\left(x \right)} \frac{d}{d x} x \]productApply the product rule to the first term.✓ Proved
- \[ = x \frac{d}{d x} \operatorname{asin}{\left(x \right)} - \frac{x}{\sqrt{1 - x^{2}}} + \operatorname{asin}{\left(x \right)} \]derivativeDifferentiate x.✓ Proved
- \[ = \operatorname{asin}{\left(x \right)} \]inverse-trig algebraDifferentiate asin(x). The two remaining terms cancel out.✓ Proved
Answer \( \operatorname{asin}{\left(x \right)} \)
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
| 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 asin is real only on [-1, 1] |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] undefined where 1 - x**2 = 0 |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 asin is real only on [-1, 1] |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 asin is real only on [-1, 1] |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: fail (error) — Step 5 applies two rules at once: it drops the constant term and differentiates the remaining part. The correct labeling would require a separate sum rule step before applying the constant rule.qwen3.6:27b-mlx: pass — The solution correctly applies differentiation rules in a step-by-step manner, with appropriate labels for each transformation. The final cancellation is handled correctly.
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-04 — The solution correctly applies differentiation rules in a step-by-step manner, with appropriate labels for each transformation. The final cancellation is handled correctly.gpt-oss:20b: fail (error) 2026-10-04 — Step 5 applies two rules at once: it drops the constant term and differentiates the remaining part. The correct labeling would require a separate sum rule step before applying the constant rule.qwen3.6:27b-mlx: pass 2026-10-04gpt-oss:20b: pass 2026-10-04
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 2026-10-04 with SymPy 1.14.0.