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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Exponential
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1992-09-02
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In mathematics, descriptive of a function in
which the variable quantity is an exponent
(an index or power to which another number or
expression is raised). Exponential functions
and series involve the constant e =
2.71828.... Napier devised natural logarithms
in 1614 with e as the base. Exponential
functions are basic mathematical functions,
written as e^x or exp x. The expression e^x
has five definitions, two of which are: (i)
e^x is the solution of the differential
equation dx/dt = x (x = 1 if t = 0); (ii) e^x
is the limiting sum of the infinite series 1
+ x + (x^2/2!) + (x^3/3!) + ... + (x^n/n!).
Curves of the form y = Ae^-ax, a > 0 are
known as decay functions; those of the form y
= Be^bx, b > 0 are growth functions.
Exponential growth is not constant. It
applies, for example, to population growth,
where the population doubles in a short time
period. A graph of population number against
time produces a curve that is
characteristically rather flat at first but
then shoots almost directly upwards.
Exponential growth is not constant. It
applies, for example, to population growth,
where the population doubles in a short time
period. A graph of population number against
time is an exponential growth function and
produces a curve that is characteristically
rather flat at first but then shoots almost
directly upwards.