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The Chain Rule

This differentiation shortcut lets us take the derivative of composed functions. (functions inside functions)

The Chain Rule

The derivative of a composition of two differentiable functions f(y)f(y) and g(x)g(x) (so that the composition f(g(x))f(g(x))is well defined), is
[f(g(x))]=f(g(x))g(x)\boxed{[f(g(x))]'=f'(g(x))g'(x)}


Wize Tip
A nice way to remember the Chain Rule is: "The derivative of the outside (keep the inside) times the derivative of the inside".

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Example: The Chain Rule

Find the derivative of the function y=(2x5)10y=(2x-5)^{10}

y=10(2x5)101×2=20(2x5)9y' =10(2x-5)^{10-1}\times2 \\ \text{} \\=\boxed{20(2x-5)^9}



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Find the derivative of the following function.

f(x)=(2x+1x2+1)3\displaystyle f(x)=\left(\frac{2x+1}{x^2+1}\right)^3

Extra Practice