In
calculus, the process of finding a
function whose
derivative is a given function. The term, sometimes used interchangeably with "antidifferentiation," is indicated symbolically with the integral sign
ò. (The
differential dx usually follows to indicate
x as the
variable.) The basic rules of integration are: (1)
ò(
f +
g)
dx =
òfdx +
ògdx (where
f and
g are functions of the variable
x), (2)
òkfdx =
kòfdx (
k is a constant), and (3)

(
C is a constant). Note that any constant value may be added onto an indefinite integral without changing its derivative. Thus, the indefinite integral of 2
x is
x2 +
C, where
C can be any real number. A definite integral is an indefinite integral evaluated over an interval. The result is not affected by the choice for the value of
C.
See also differentiation.
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