The Product Rule for Derivatives Explained Simply

The product rule for derivatives is often needed in school and may seem complicated. Here you will learn how to differentiate products easily!

Explanation

Definition

The product rule is a rule used in differentiation when you want to differentiate two functions that are multiplied together. When differentiating products, you need to apply the product rule. The product rule formula is:

(u(x) \cdot v(x))' = u'(x) \cdot v(x) + u(x) \cdot v'(x)

Procedure

Scheme

To differentiate products, you must first identify the two functions u(x) and v(x). Then differentiate each function separately and insert these derivatives into the product rule formula. Afterwards, simplify the expression.

f'(x) = u'(x) \cdot v(x) + u(x) \cdot v'(x)

Examples

Differentiate the function f(x) = x \cdot \sin(x).

Let u(x) = x and v(x) = \sin(x). Then we have u'(x) = 1 and v'(x) = \cos(x).

Inserting into the product rule formula gives:

f'(x) = 1 \cdot \sin(x) + x \cdot \cos(x) = \sin(x) + x \cdot \cos(x)

Differentiate the function f(x) = (2x^2 + 3) \cdot e^{x}.

Let u(x) = 2x^2 + 3 and v(x) = e^{x}. Then we have u'(x) = 4x and v'(x) = e^{x}.

f'(x) = 4x \cdot e^{x} + (2x^2 + 3) \cdot e^{x} = e^{x}(4x + 2x^2 + 3)

Note

Summary
  • The product rule is used to differentiate the product of two functions.
  • The product rule formula is: (u(x) \cdot v(x))' = u'(x) \cdot v(x) + u(x) \cdot v'(x).

Exercises

1 / 3
Differentiate the function
f(x) = x \cdot \cos(x)
2 / 3
Differentiate the function
f(x) = (3x - 2) \cdot \ln(x)
3 / 3
Differentiate the function
f(x) = (x^2 + 1) \cdot (\sin(x) + \cos(x))
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