The chain rule for differentiation simply explained

The chain rule for differentiation often causes confusion in school. Here you learn easily how to differentiate any composite function!

Explanation

Definition

The chain rule is used to differentiate a composite function. A composite function consists of an outer function and an inner function. The chain rule states that you first differentiate the outer function and then multiply by the derivative of the inner function. The chain rule formula is:

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

Procedure

Scheme

To differentiate a composite function, follow these steps:

1. Determine the outer function u and the inner function v.

2. Differentiate the outer function u with respect to v.

3. Differentiate the inner function v with respect to x.

4. Multiply both derivatives together to get the derivative of the composite function.

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

Examples

Differentiate the function f(x) = (3x + 2)^2 .

Outer function: u(v) = v^2, inner function: v(x) = 3x + 2.
u'(v) = 2v, v'(x) = 3.

f'(x) = 2 \cdot (3x + 2) \cdot 3 = 6(3x + 2)

Differentiate the function f(x) = \sin(4x^2) .

Outer function: u(v) = \sin(v), inner function: v(x) = 4x^2.
u'(v) = \cos(v), v'(x) = 8x.

f'(x) = \cos(4x^2) \cdot 8x = 8x \cos(4x^2)

Note

Summary
  • The chain rule is used to differentiate composite functions.
  • Derivative of the outer function multiplied by the derivative of the inner function gives the overall derivative.

Exercises

1 / 3
Differentiate the function
f(x) = (5x - 1)^3
2 / 3
Differentiate the function
f(x) = \sqrt{2x^3 + 4}
3 / 3
Differentiate the function
f(x) = e^{\sin(3x^2)}
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