Antiderivative
Indefinite Integral
Checking
Indefinite Integral Formulas
Indefinite
Integrals
One interpretation of the derivative of a function is that the drivative gives
you the slope
of the graph of the function. Given a function, you can find the slope at a
specific point
of the graph of the function by finding the value of the derivative of the function
at that
specific point.
For example, if the function is
then to find the slope of the graph of the function at the point ,
you find the
derivative of the function
and substitute .
At that point the slope of the graph is
The problem going in the opposite direction is to find the function itself when
you
are first given the derivative of the function.
For this example, the problem would be to find
when you are given that
.
The solution of this problem brings in the integral calculus.
The monomial
is simple enough so it is not so hard to determine that
works for a solution.
So
is a solution to the problem.
But
,
, and
all work too, as you can verify by taking their drivative.
Each of these functions is called an antiderivative of .
In fact, any combination of the form
, where C is a constant, works.
The general form
is called the indefinite integral of
.
The notation is
is called the constant
of integration.
In general,
where
.
Checking
an Indefinite Integral
Is the integral correct ?
You can check by differentiating the right side of the equation. If you get
the integrand
as the result, then the integral is correct.
The integral is correct !
See Examples 2 - 3, pages 315 - 316.
Indefinite
Integral Formulas
Here are some indefinite integral formulas from Table 4.1, page 315, of the
text
and their proofs.
Formula 1]
because
The restriction
is needed because when
,
the denominator become
.
Later, the formula will be extended to the case where .
The extension will involve a transcendental function, the natural logarithm
of .
Formula 2]
because
Formula 6]
because
By the quotient rule for derivatives
Some examples of using the above formulas are
and
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Equations Initial Value Problems
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