Evaluate second derivative of ln(x): animated lesson
A narrated, step-by-step derivatives video lesson with captions. Final answer: f''(x) = -(1 / x²).
Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.
Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)
Steps on screen
- 1. The problemFinding a derivative
- 2. Steps, part 1
- Derivative number 1
- d/dx[ln x] = 1/x
- Simplify the first derivative
- Derivative number 2
- 3. Steps, part 2
- Quotient rule: (u/v)′ = (u′v − uv′)/v²
- Simplify the second derivative
- 4. The answer
f''(x) = -(1 / x²)
- 5. Check
- Cross-checked numerically against an independent symbolic differentiator at 8 sample points ✓
Transcript
The problem. Here is the problem: ln(x). Find the second derivative of ln(x) with respect to x.
Steps, part 1. Derivative number 1. d by d x[ln x] equals 1/x. Simplify the first derivative. Derivative number 2.
Steps, part 2. Quotient rule: (u/v) prime equals (u prime v minus uv prime )/v squared. Simplify the second derivative.
The answer. So the answer is f prime prime (x) equals -(1 / x squared). The derivative is built from the outside in: sums split into terms, constants factor out, products and quotients use their rules, and every composite function multiplies by the derivative of its inside (chain rule).
Check. Cross-checked numerically against an independent symbolic differentiator at 8 sample points, which checks out.
About derivatives
Differentiate with the power, product, quotient and chain rules, including higher derivatives.
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