So far we have worked with rational bases for exponential functions. For most real-world phenomena, however,
e is used as the base for exponential functions. Exponential models that use
as the base are called
continuous growth or decay models . We see these models in finance, computer science, and most of the sciences, such as physics, toxicology, and fluid dynamics.
The continuous growth/decay formula
For all real numbers
and all positive numbers
and
continuous growth or decay is represented by the formula
where
is the initial value,
is the continuous growth rate per unit time,
and
is the elapsed time.
If
, then the formula represents continuous growth. If
, then the formula represents continuous decay.
For business applications, the continuous growth formula is called the continuous compounding formula and takes the form
where
is the principal or the initial invested,
is the growth or interest rate per unit time,
and
is the period or term of the investment.
Given the initial value, rate of growth or decay, and time
solve a continuous growth or decay function.
Use the information in the problem to determine
, the initial value of the function.
Use the information in the problem to determine the growth rate
If the problem refers to continuous growth, then
If the problem refers to continuous decay, then
Use the information in the problem to determine the time
Substitute the given information into the continuous growth formula and solve for
Calculating continuous growth
A person invested $1,000 in an account earning a nominal 10% per year compounded continuously. How much was in the account at the end of one year?
Since the account is growing in value, this is a continuous compounding problem with growth rate
The initial investment was $1,000, so
We use the continuous compounding formula to find the value after
year:
Radon-222 decays at a continuous rate of 17.3% per day. How much will 100 mg of Radon-222 decay to in 3 days?
Since the substance is decaying, the rate,
, is negative. So,
The initial amount of radon-222 was
mg, so
We use the continuous decay formula to find the value after
days:
Using the data in
[link] , how much radon-222 will remain after one year?
3.77E-26 (This is calculator notation for the number written as
in scientific notation. While the output of an exponential function is never zero, this number is so close to zero that for all practical purposes we can accept zero as the answer.)
Astronomy (from Ancient Greek ἀστρονομία (astronomía) 'science that studies the laws of the stars') is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution.
Rafael
vjuvu
Elgoog
what is big bang theory?
Rosemary
what type of activity astronomer do?
Rosemary
No
Richard
the big bang theory is a theory which states that all matter was compressed together in one place the matter got so unstable it exploded releasing All its contents in the form of hydrogen
according to the theory of astronomers why the moon is always appear in an elliptical orbit?
Gatjuol
hi !!! I am new in astronomy....
I have so many questions in mind ....
all of scientists of the word they just give opinion only.
but they never think true or false ...
i respect all of them...
I believes whole universe depending
on true ...থিউরি
Govinda
hello
Jackson
hi
Elyana
we're all stars and galaxies a part of sun. how can science prove thx with respect old ancient times picture or books..or anything with respect to present time .but we r a part of that universe
there many theory to born universe but what is the reality of big bang theory to born universe
Asmit
what is the exact value of π?
Nagalakshmi
by big bang
universal
there are many theories regarding this it's on you believe any theory that you think is true ex. eternal inflation theory, oscillation model theory, multiple universe theory the big bang theory etc.
Aarya
I think after Big Bang!
Michele
from where on earth could u observe all the stars during the during the course of an year
is that so. the question was in the end of this chapter
Karuna
in theory, you could see them all from the equator (though over the course of a year, not at pne time). stars are measured in "declination", which is how far N or S of the equator (90* to -90*). Polaris is the North star, and is ALMOST 90* (+89*).
So it would just barely creep over the horizon.
Christopher
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