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 . (The differential dx usually follows to indicate x as the variable.) The basic rules of integration are: (1) (f + g)dx = fdx + gdx (where f and g are functions of the variable x), (2) kfdx = kfdx (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 2x 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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