MatteSkolen kalkulus What is the product rule?
VG3 kalkulus Quiz

What is the product rule?

The product rule is used when differentiating a product of two functions.

📅 1. May 2026 👁️ 2 views 📂 kalkulus 🇳🇴 Les på norsk

When two functions are multiplied together, we cannot simply differentiate each separately. We must use the product rule.

[u · v]' = u' · v + u · v'

Differentiate the first and keep the second, plus keep the first and differentiate the second.

Memory tip: "Derivative-first times second, plus first times derivative-second"

Examples

Example 1: Differentiate h(x) = x² · sin(x)

u = x² → u' = 2x
v = sin(x) → v' = cos(x)
h'(x) = 2x · sin(x) + x² · cos(x)

Example 2: Differentiate h(x) = eˣ · ln(x)

u = eˣ → u' = eˣ
v = ln(x) → v' = 1/x
h'(x) = eˣ · ln(x) + eˣ · (1/x) = eˣ(ln(x) + 1/x)

Mathematics is the queen of the sciences and number theory is the queen of mathematics.

— Carl Friedrich Gauss (1777–1855)

🧠 Test yourself

Question 1 of 5

What is the product rule?

Read also

← Back to kalkulus Front page →