Let y = (2x² + 3)⁵. Find dy/dx at x = 1.

$f'(a) = \displaystyle\lim_{h \to 0}\frac{f(a + h) - f(a)}{h}$, and $f$ is differentiable at $a$ when the left and right derivatives are equal. A differentiable function is continuous. The chain rule is $\dfrac{dy}{dx} = \dfrac{dy}{du}\times\dfrac{du}{dx}$.