Integral

: This article deals with the concept of an integral in calculus. For other meanings of "integral" see integration and integral (disambiguation).

Definitions by means of an integral

Several mathematical functions and constants can be defined by using an integral. The natural logarithm is usually defined as

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:ln x = int_1^x ! rac{1}{t} dt.

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The mathematical constant e may then be defined as the number x > 0 such that

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:ln x =int_1^x ! rac{1}{t} dt = 1.

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