∫Calc Practice

Derivative of \( \displaystyle x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}} \)

Problem 2.1491 · hard Beautiful

Differentiate \( \displaystyle f(x) = x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}} \).
  1. \[ \frac{d}{d x} \left(x \operatorname{asin}{\left(x \right)} + \sqrt{1 - x^{2}}\right) \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{d}{d x} \sqrt{1 - x^{2}} \]
    sum rewriteApply the sum rule. Rewrite the square root as a power.✓ Proved
  3. \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{\frac{d}{d x} \left(1 - x^{2}\right)}{2 \sqrt{1 - x^{2}}} \]
    chainApply the chain rule to the second term.✓ Proved
  4. \[ = \frac{d}{d x} x \operatorname{asin}{\left(x \right)} + \frac{\frac{d}{d x} \left(- x^{2}\right)}{2 \sqrt{1 - x^{2}}} \]
    constantApply the sum rule to the inner expression.✓ Proved
  5. \[ = - \frac{x}{\sqrt{1 - x^{2}}} + \frac{d}{d x} x \operatorname{asin}{\left(x \right)} \]
    power algebraDifferentiate the term -x**2. Simplify the constants.✓ Proved
  6. \[ = x \frac{d}{d x} \operatorname{asin}{\left(x \right)} - \frac{x}{\sqrt{1 - x^{2}}} + \operatorname{asin}{\left(x \right)} \frac{d}{d x} x \]
    productApply the product rule to the first term.✓ Proved
  7. \[ = x \frac{d}{d x} \operatorname{asin}{\left(x \right)} - \frac{x}{\sqrt{1 - x^{2}}} + \operatorname{asin}{\left(x \right)} \]
    derivativeDifferentiate x.✓ Proved
  8. \[ = \operatorname{asin}{\left(x \right)} \]
    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
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
undefined where 1 - x**2 = 0
11✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
asin is real only on [-1, 1]
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
asin is real only on [-1, 1]
answer, a second way✓ Provedsympy 1.14.0SymPy 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 2026-10-04
  • gpt-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.