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