Math2.org Math Tables: Differentiation Identities

(Math)

Definitions of the Derivative:
\[ \frac{df}{dx} = \lim<sub>h \to 0<sup>+</sup></sub> \frac{f(x+h) - f(x)}{h} \] (right sided)
\[ \frac{df}{dx} = \lim<sub>h \to 0<sup>-</sup></sub> \frac{f(x+h) - f(x)}{h} \] (left sided)
\[ \frac{df}{dx} = \lim<sub>h \to 0</sub> \frac{f(x+h) - f(x)}{h} \] (both sided)

\[ \frac{d}{dx} \int_a^x f(t) \, dt = f(x) \] (Fundamental Theorem for Derivatives)


(d/dx)c f(x) = c proof
(d/dx)f(x) (c is a constant)

(d/dx) (f(x) + g(x)) = (d/dx) f(x) + (d/dx) g(x) proof

(d/dx) f(g(x)) = (d/dg) f(g) * (d/dx) g(x) (chain rule) proof

(d/dx) f(x)g(x) = f' (x)g(x) + f(x)g '(x) (product rule)

\[ \frac{d}{dx} \frac{f(x)}{g(x)} = \frac{f'(x)g(x) - f(x)g'(x)}{g(x)^2} \] (quotient rule)


Partial Differentiation Identities

if f( x(r,s), y(r,s) )

\[ \frac{\partial f}{\partial r}
  = \frac{\partial f}{\partial x} \frac{\partial x}{\partial r}
  + \frac{\partial f}{\partial y} \frac{\partial y}{\partial r}
  \]
\[ \frac{\partial f}{\partial s}
  = \frac{\partial f}{\partial x} \frac{\partial x}{\partial s}
  + \frac{\partial f}{\partial y} \frac{\partial y}{\partial s}
  \]

if f( x(r,s) )

\[ \frac{\partial f}{\partial r}
  = \frac{\partial f}{\partial x} \frac{\partial x}{\partial r}
  \]
\[ \frac{\partial f}{\partial s}
  = \frac{\partial f}{\partial x} \frac{\partial x}{\partial s}
  \]