Chain rule

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The chain rule is a way of finding the derivative of a function. It is used where the function is in another function. This is called a composite function.

If F(x) equals two functions that we can take a derivative of, such as:

F(x)=f(g(x))

then the derivative, F prime, is

F'(x)=f'(g(x))g'(x)

Steps[change | edit source]

1. Find the derivative of the outside function (all of it at once).

2. Find the derivative of the inside function (the bit between the brackets).

3. Multiply the answer from the first step by the answer from the second step.

Example;
F(x)=(x^2+5)^3
F(x)=3(x^2+5)^2
F'(x)=3(x^2+5)^2(2x)
F'(x)=6x(x^2+5)^2


In this example, the cubed sign (3) is the outside function and x^2+5 is the inside function. The derivative of the outside function would be 3x^2, where the inside function is plugged in for x. The derivative of the inside function would be 2x, which is multiplied by 3(x^2+5)^2 to get 6x(x^2+5)^2.