Differentiation rules

This is a summary of differentiation rules, that is, rules for computing the derivative of a function in calculus.

Elementary rules of differentiation

Unless otherwise stated, all functions are functions of real, R, numbers that return real, R, values; although more generally, the formulae below apply wherever they are well defined[1][2] - including complex, C, numbers [3].
Differentiation is linear
Main article: Linearity of differentiation

For any functions f and g and any real numbers a and b the derivative of the function h(x) = af(x) + bg(x) with respect to x is

\( h'(x) = a f'(x) + b g'(x).\, \)

In Leibniz's notation this is written as:

\( \frac{d(af+bg)}{dx} = a\frac{df}{dx} +b\frac{dg}{dx}. \)

Special cases include:

The constant multiple rule

\( (af)' = af' \, \)

The sum rule

\( (f + g)' = f' + g'\, \)

The subtraction rule

\( (f - g)' = f' - g'.\, \)

The product rule (Leibniz rule)
Main article: Product rule

For the functions f and g, the derivative of the function h(x) = f(x) g(x) with respect to x is

\( h'(x) = f'(x) g(x) + f(x) g'(x).\, \)

In Leibniz's notation this is written

\( \frac{d(fg)}{dx} = \frac{df}{dx} g + f \frac{dg}{dx}.\)

The chain rule
Main article: Chain rule

The derivative of the function of a function h(x) = f(g(x)) with respect to x is

\( h'(x) = f'(g(x)) g'(x).\, \)

In Leibniz's notation this is written as:

\( \frac{dh}{dx} = \frac{df}{dg} \frac{dg}{dx}.\, \)

However, by relaxing the interpretation of h as a function, this is often simply written

\( \frac{dh}{dx} = \frac{dh}{dg} \frac{dg}{dx}.\, \)

The inverse function rule
Main article: inverse functions and differentiation

If the function f has an inverse function g, meaning that g(f(x)) = x and f(g(y)) = y, then

\( g' = \frac{1}{f'\circ g}.\, \)

In Leibniz notation, this is written as

\( \frac{dx}{dy} = \frac{1}{dy/dx}. \)

Power laws, polynomials, quotients, and reciprocals
The polynomial or elementary power rule
Main article: Power rule

If f(x) = x^n, for any integer n then

\( f'(x) = nx^{n-1}.\, \)

Special cases include:

Constant rule: if f is the constant function f(x) = c, for any number c, then for all x, f′(x) = 0.
if f(x) = x, then f′(x) = 1. This special case may be generalized to:

The derivative of a linear function is constant: if f(x) = ax + b, then f′(x) = a.

Combining this rule with the linearity of the derivative permits the computation of the derivative of any polynomial.
The reciprocal rule
Main article: Reciprocal rule

The derivative of h(x) = 1/f(x) for any (nonvanishing) function f is:

\( h'(x) = -\frac{f'(x)}{[f(x)]^2}.\ \)

In Leibniz's notation, this is written

\( \frac{d(1/f)}{dx} = -\frac{1}{f^2}\frac{df}{dx}.\, \)

The reciprocal rule can be derived from the chain rule and the power rule.
The quotient rule
Main article: Quotient rule

If f and g are functions, then:

\( \left(\frac{f}{g}\right)' = \frac{f'g - g'f}{g^2}\quad \) wherever g is nonzero.

This can be derived from reciprocal rule and the product rule. Conversely (using the constant rule) the reciprocal rule may be derived from the special case f(x) = 1.
Generalized power rule
Main article: Power rule

The elementary power rule generalizes considerably. The most general power rule is the functional power rule: for any functions f and g,

\( (f^g)' = \left(e^{g\ln f}\right)' = f^g\left(f'{g \over f} + g'\ln f\right),\quad \)

wherever both sides are well defined.

Special cases:

If f(x) = xa, f′(x) = axa − 1 when a is any real number and x is positive.
The reciprocal rule may be derived as the special case where g(x) = −1.

Derivatives of exponential and logarithmic functions

\( \left(c^{ax}\right)' = {c^{ax} \ln c \cdot a } ,\qquad c > 0 \)

note that the equation above is true for all c, but the derivative for c < 0 yields a complex number.

\( \left(e^x\right)' = e^x \)

\( \left( \log_c x\right)' = {1 \over x \ln c} , \qquad c > 0, c \ne 1 \)

the equation above is also true for all c but yields a complex number.

\( \left( \ln x\right)' = {1 \over x} ,\qquad x \ne 0 \)

\( \left( \ln |x|\right)' = {1 \over x} \)

\( \left( x^x \right)' = x^x(1+\ln x) \)

The derivative of the natural logarithm with a generalised functional argument f(x) is

\( \frac{d}{dx}[\ln(f(x))] = \frac{f'(x)}{f(x)} \)

By applying the change-of-base identity, the derivative for other bases is

\( \frac{d}{dx} \log_b(x) = \frac{d}{dx} \frac {\ln(x)}{\ln(b)} = \frac{1}{x \ln(b)} = \frac{\log_b(e)}{x}. \)

Logarithmic derivatives

The logarithmic derivative is another way of stating the rule for differentiating the logarithm of a function (using the chain rule):

\( (\ln f)'= \frac{f'}{f} \quad \) wherever f is positive.

Derivatives of trigonometric functions
For more details on this topic, see Differentiation of trigonometric functions.
\( (\sin x)' = \cos x \, (\arcsin x)' = { 1 \over \sqrt{1 - x^2}} \, \)
\( (\cos x)' = -\sin x \, (\arccos x)' = -{1 \over \sqrt{1 - x^2}} \, \)
\( (\tan x)' = \sec^2 x = { 1 \over \cos^2 x} = 1 + \tan^2 x \, (\arctan x)' = { 1 \over 1 + x^2} \, \)
\( (\sec x)' = \sec x \tan x \, (\operatorname{arcsec} x)' = { 1 \over |x|\sqrt{x^2 - 1}} \, \)
\( (\csc x)' = -\csc x \cot x \, (\operatorname{arccsc} x)' = -{1 \over |x|\sqrt{x^2 - 1}} \, \)
\( (\cot x)' = -\csc^2 x = { -1 \over \sin^2 x} = -(1 + \cot^2 x)\, (\operatorname{arccot} x)' = -{1 \over 1 + x^2} \, \)
Derivatives of hyperbolic functions
\( ( \sinh x )'= \cosh x = \frac{e^x + e^{-x}}{2} (\operatorname{arsinh}\,x)' = { 1 \over \sqrt{x^2 + 1}} \)
\( (\cosh x )'= \sinh x = \frac{e^x - e^{-x}}{2} (\operatorname{arcosh}\,x)' = {\frac {1}{\sqrt{x^2-1}}} \)
\( (\tanh x )'= {\operatorname{sech}^2\,x} (\operatorname{artanh}\,x)' = { 1 \over 1 - x^2} \)
\( (\operatorname{sech}\,x)' = - \tanh x\,\operatorname{sech}\,x (\operatorname{arsech}\,x)' = -{1 \over x\sqrt{1 - x^2}} \)
\( (\operatorname{csch}\,x)' = -\,\operatorname{coth}\,x\,\operatorname{csch}\,x (\operatorname{arcsch}\,x)' = -{1 \over |x|\sqrt{1 + x^2}} \)
\( (\operatorname{coth}\,x )' = -\,\operatorname{csch}^2\,x (\operatorname{arcoth}\,x)' = { 1 \over 1 - x^2} \)

Derivatives of special functions

Gamma function

\( (\Gamma(x))' = \int_0^\infty t^{x-1} e^{-t} \ln t\,dt (\Gamma(x))' = \Gamma(x) \left(\sum_{n=1}^\infty \left(\ln\left(1 + \dfrac{1}{n}\right) - \dfrac{1}{x + n}\right) - \dfrac{1}{x}\right) = \Gamma(x) \psi(x)\)

Riemann Zeta function

\( (\zeta(x))' = -\sum_{n=1}^\infty \frac{\ln n}{n^x} = -\frac{\ln 2}{2^x} - \frac{\ln 3}{3^x} - \frac{\ln 4}{4^x} - \cdots \! \)

\( (\zeta(x))' = -\sum_{p \text{ prime}} \frac{p^{-x} \ln p}{(1-p^{-x})^2}\prod_{q \text{ prime}, q \neq p} \frac{1}{1-q^{-x}} \! \)
Derivatives to nth order

Some rules exist for computing the nth derivative of functions, where n is a positive integer. These include:
Faà di Bruno's formula
Main article: faà di Bruno's formula

If f and g are n times differentiable, then

\( \frac{d^n}{d x^n} [f(g(x))]= n! \sum_{\{k_m\}}^{} f^{(r)}(g(x)) \prod_{m=1}^n \frac{1}{k_m!} \left(g^{(m)}(x) \right)^{k_m} \)

where \( r = \sum_{m=1}^{n-1} k_m and the set \{k_m\} \) consists of all non-negative integer solutions of the Diophantine equation \( \sum_{m=1}^{n} m k_m = n. \)
General Leibniz rule
Main article: General Leibniz rule

If f and g are n times differentiable, then

\( \frac{d^n}{dx^n}[f(x)g(x)] = \sum_{k=0}^{n} \binom{n}{k} \frac{d^{n-k}}{d x^{n-k}} f(x) \frac{d^k}{d x^k} g(x)

See also

Derivative
Differential calculus
Vector calculus identities
Differentiable function
Differential of a function
Limit of a function
Function (mathematics)
List of mathematical functions
Trigonometric functions
Inverse trigonometric functions
Hyperbolic functions
Inverse hyperbolic functions
Matrix calculus

References

^ Calculus (5th edition), F. Ayres, E. Mendelson, Schuam's Outline Series, 2009, ISBN 978-0-07-150861-2.
^ Advanced Calculus (3rd edition), R. Wrede, M.R. Spiegel, Schuam's Outline Series, 2010, ISBN 978-0-07-162366-7.
^ Complex Variables, M.R. Speigel, S. Lipschutz, J.J. Schiller, D. Spellman, Schaum's Outlines Series, McGraw Hill (USA), 2009, ISBN 978-0-07-161569-3

Sources and further reading

These rules are given in many books, both on elementary and advanced calculus, in pure and applied mathematics. Those in this article (in addition to the above references) can be found in:

Mathematical Handbook of Formulas and Tables (3rd edition), S. Lipschutz, M.R. Spiegel, J. Liu, Schuam's Outline Series, 2009, ISBN 978-0-07-154855-7.
The Cambridge Handbook of Physics Formulas, G. Woan, Cambridge University Press, 2010, ISBN 978-0-521-57507-2.
Mathematical methods for physics and engineering, K.F. Riley, M.P. Hobson, S.J. Bence, Cambridge University Press, 2010, ISBN 978-0-521-86153-3
NIST Handbook of Mathematical Functions, F. W. J. Olver, D. W. Lozier, R. F. Boisvert, C. W. Clark, Cambridge University Press, 2010, ISBN 9780521192255.

External links

Derivative calculator with formula simplification
A Table of Derivatives