### 15.3.3 Rules

This subsection is not completed yet, but in the meantime here are some practice questions.

Remember:
$\frac{\dif }{\dif x} f(ax) = af’(ax)$

Remember:
The product rule states that: $\frac{\dif }{\dif x}\left(f(x)g(x)\right) = f’(x)g(x) + f(x)g’(x)$

Remember:
The quotient rule states that: $\frac{\dif }{\dif x}\frac{f(x)}{g(x)} = \frac{f’(x)g(x) - f(x)g’(x)}{g(x)^2}$

Remember:
The chain rule states that: $\frac{\dif }{\dif x}f(g(x)) = f’(g(x))g’(x)$ I think of it as ‘differentiate the outer function, leaving the inner function alone, then multiply by the derivative of the inner function.’