e constant

e constant or Euler's number is a mathematical constant. The e constant is real and irrational number.

e = 2.718281828459...

• Definition of e
• Properties of e
  • Reciprocal of e
  • Derivatives of e
  • Integrals of e
• Base e logarithm
• Exponential function
• Euler's formula

Definition of e

The e constant is defined as the limit:

Alternative definitions

The e constant is defined as the limit:

The e constant is defined as the infinite series:

Properties of e

Reciprocal of e

The reciprocal of e is the limit:

Derivatives of e

The derivative of the exponential function is the exponential function:

(e ^x)' = e^x

The derivative of the natural logarithm function is the reciprocal function:

(log_e x)' = (ln x)' = 1/x

Integrals of e

The indefinite integral of the exponential function e^x is the exponential function e^x.

∫ e^x dx = e^x+c

The indefinite integral of the natural logarithm function log_e x is:

∫ log_e x dx = ∫ lnx dx = x ln x - x +c

The definite integral from 1 to e of the reciprocal function 1/x is 1:

Base e logarithm

The natural logarithm of a number x is defined as the base e logarithm of x:

ln x = log_e x

Exponential function

The exponential function is defined as:

f (x) = exp(x) = e^x

Euler's formula

The complex number e ^iθ has the identity:

e^iθ = cos(θ) + i sin(θ)

i is the imaginary unit (the square root of -1).

θ is any real number.