Derivative of (ln(3x-2))/(cos(e^(x)+1)): animated lesson
A narrated, step-by-step derivatives video lesson with captions. Final answer: f'(x) = (3 / (3 x - 2) + ln(3 x - 2)·sin(e^x + 1)·e^x / cos(e^x + 1)) / cos(e^x + 1).
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 (0.7 MB) · Captions (WebVTT)
Steps on screen
- 1. The problemFinding a derivative
- 2. Steps, part 1
- Quotient rule: (u/v)′ = (u′v − uv′)/v²
- Chain rule — d/dx[cos u] = −sin u · u′
- Sum rule: differentiate each term separately
- Exponential rule: d/dx[eᵘ] = eᵘ·u′
- 3. Steps, part 2
- Chain rule — d/dx[ln u] = u′/u
- Difference rule: differentiate each term separately
- Constant multiple rule
- Combine and simplify
- 4. The answer
f'(x) = (3 / (3 x - 2) + ln(3 x - 2)·sin(e^x + 1)·e^x / cos(e^x + 1)) / cos(e^x + 1)
- 5. Check
- Cross-checked numerically against an independent symbolic differentiator at 8 sample points ✓
Transcript
The problem. Here is the problem: derivative of (ln(3x minus 2))/(cos(e to the power x plus 1)). Find the derivative of (ln(3 x minus 2)) / (cos(e to the power x plus 1)) with respect to x.
Steps, part 1. Quotient rule: (u/v) prime equals (u prime v minus uv prime )/v squared. Chain rule — d by d x[cos u] equals negative sin u times u prime. Sum rule: differentiate each term separately. Exponential rule: d by d x[eᵘ] equals eᵘ times u prime.
Steps, part 2. Chain rule — d by d x[ln u] equals u prime /u. Difference rule: differentiate each term separately. Constant multiple rule. Combine and simplify.
The answer. So the answer is f prime of x equals (3 / (3 x minus 2) plus ln(3 x minus 2) times sin(e to the power x plus 1) times e to the power x / cos(e to the power x plus 1)) / cos(e to the power x plus 1). 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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