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What is differentiation?

Differentiation finds the instantaneous rate of change of a function — how fast something is changing at a specific point.

📅 30. April 2026 👁️ 7 views 📂 kalkulus 🇳🇴 Les på norsk
🎮 Try it yourself — interactive!
See the tangent line move along the curve and the derivative calculated live.
→ Open interactive parabola (with tangent)

The intuitive idea

A speedometer shows your speed right now — not your average speed for the whole trip. This is the essence of differentiation: the instantaneous rate of change.

Notation

f'(x) or dy/dx

Differentiation rules

f(x)f'(x)Example
c (constant)0f(x)=7 → 0
x1f(x)=x → 1
xⁿn·xⁿ⁻¹f(x)=x³ → 3x²
ax+baf(x)=3x+2 → 3

Step-by-step example

Differentiate f(x) = 4x³ + 2x² - 5x + 1

f'(x) = 4·3x² + 2·2x - 5 + 0
f'(x) = 12x² + 4x - 5

What is differentiation used for?

  • Finding maximum and minimum points (where f'(x) = 0)
  • Analysing whether a function is increasing or decreasing
  • Speed and acceleration in physics
  • Optimisation in economics
Power rule memory trick:
Bring down the exponent and subtract 1:
xⁿ → n·xⁿ⁻¹

Nature is written in mathematical language, and the letters are triangles, circles and other geometrical figures.

— Galileo Galilei (1564–1642)

🧠 Test yourself

Question 1 of 3

What is the derivative of f(x) = x3?

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