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DerivativesCalculusCollegeabout 0:44

Differentiate tan(3x): animated lesson

A narrated, step-by-step derivatives video lesson with captions. Final answer: f'(x) = 3sec(3x)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 (0.3 MB) · Captions (WebVTT)

Steps on screen

  1. 1. The problem
    Finding a derivative
    ddx[tan⁡(3x)]\frac{d}{dx}\left[\tan\left(3x\right)\right]
  2. 2. Step by step
    1. ddx[tan⁡(3x)]=3sec⁡(3x)2\frac{d}{dx}\left[\tan\left(3x\right)\right] = 3 {\sec\left(3x\right)}^{2}
      Chain rule — d/dx[tan u] = sec² u · u′
    2. ddx[3x]=3\frac{d}{dx}\left[3x\right] = 3
      Constant multiple rule
    3. f′(x)=3sec⁡(3x)2f'(x) = 3 {\sec\left(3x\right)}^{2}
      Combine and simplify
  3. 3. The answer
    f′(x)=3sec⁡(3x)2f'(x) = 3 {\sec\left(3x\right)}^{2}

    f'(x) = 3sec(3x)²

  4. 4. Check
    • Cross-checked numerically against an independent symbolic differentiator at 8 sample points ✓

Transcript

The problem. Here is the problem: differentiate tan(3x). Find the derivative of tan(3 x) with respect to x.

Step by step. Chain rule — d by d x[tan u] equals sec squared u times u prime. Constant multiple rule. Combine and simplify.

The answer. So the answer is f prime of x equals 3sec(3x) 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.

Differentiate tan(3x): Derivatives Step-by-Step Lesson